/*
 * Copyright 2019 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Author: AMD
 */

#include <drm/drm_dsc.h>
#include "dc_hw_types.h"
#include "dsc.h"
#include <drm/dp/drm_dp_helper.h>
#include "dc.h"
#include "rc_calc.h"
#include "fixed31_32.h"

/* This module's internal functions */

/* default DSC policy target bitrate limit is 16bpp */
static uint32_t dsc_policy_max_target_bpp_limit = 16;

/* default DSC policy enables DSC only when needed */
static bool dsc_policy_enable_dsc_when_not_needed;

static bool dsc_policy_disable_dsc_stream_overhead;

#ifndef MAX
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
#endif
#ifndef MIN
#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
#endif

/* Forward Declerations */
static bool decide_dsc_bandwidth_range(
                const uint32_t min_bpp_x16,
                const uint32_t max_bpp_x16,
                const uint32_t num_slices_h,
                const struct dsc_enc_caps *dsc_caps,
                const struct dc_crtc_timing *timing,
                struct dc_dsc_bw_range *range);

static uint32_t compute_bpp_x16_from_target_bandwidth(
                const uint32_t bandwidth_in_kbps,
                const struct dc_crtc_timing *timing,
                const uint32_t num_slices_h,
                const uint32_t bpp_increment_div,
                const bool is_dp);

static void get_dsc_enc_caps(
                const struct display_stream_compressor *dsc,
                struct dsc_enc_caps *dsc_enc_caps,
                int pixel_clock_100Hz);

static bool intersect_dsc_caps(
                const struct dsc_dec_dpcd_caps *dsc_sink_caps,
                const struct dsc_enc_caps *dsc_enc_caps,
                enum dc_pixel_encoding pixel_encoding,
                struct dsc_enc_caps *dsc_common_caps);

static bool setup_dsc_config(
                const struct dsc_dec_dpcd_caps *dsc_sink_caps,
                const struct dsc_enc_caps *dsc_enc_caps,
                int target_bandwidth_kbps,
                const struct dc_crtc_timing *timing,
                int min_slice_height_override,
                int max_dsc_target_bpp_limit_override_x16,
                struct dc_dsc_config *dsc_cfg);

static bool dsc_buff_block_size_from_dpcd(int dpcd_buff_block_size, int *buff_block_size)
{

        switch (dpcd_buff_block_size) {
        case DP_DSC_RC_BUF_BLK_SIZE_1:
                *buff_block_size = 1024;
                break;
        case DP_DSC_RC_BUF_BLK_SIZE_4:
                *buff_block_size = 4 * 1024;
                break;
        case DP_DSC_RC_BUF_BLK_SIZE_16:
                *buff_block_size = 16 * 1024;
                break;
        case DP_DSC_RC_BUF_BLK_SIZE_64:
                *buff_block_size = 64 * 1024;
                break;
        default: {
                        dm_error("%s: DPCD DSC buffer size not recognized.\n", __func__);
                        return false;
                }
        }

        return true;
}


static bool dsc_line_buff_depth_from_dpcd(int dpcd_line_buff_bit_depth, int *line_buff_bit_depth)
{
        if (0 <= dpcd_line_buff_bit_depth && dpcd_line_buff_bit_depth <= 7)
                *line_buff_bit_depth = dpcd_line_buff_bit_depth + 9;
        else if (dpcd_line_buff_bit_depth == 8)
                *line_buff_bit_depth = 8;
        else {
                dm_error("%s: DPCD DSC buffer depth not recognized.\n", __func__);
                return false;
        }

        return true;
}


static bool dsc_throughput_from_dpcd(int dpcd_throughput, int *throughput)
{
        switch (dpcd_throughput) {
        case DP_DSC_THROUGHPUT_MODE_0_UNSUPPORTED:
                *throughput = 0;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_170:
                *throughput = 170;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_340:
                *throughput = 340;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_400:
                *throughput = 400;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_450:
                *throughput = 450;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_500:
                *throughput = 500;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_550:
                *throughput = 550;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_600:
                *throughput = 600;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_650:
                *throughput = 650;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_700:
                *throughput = 700;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_750:
                *throughput = 750;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_800:
                *throughput = 800;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_850:
                *throughput = 850;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_900:
                *throughput = 900;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_950:
                *throughput = 950;
                break;
        case DP_DSC_THROUGHPUT_MODE_0_1000:
                *throughput = 1000;
                break;
        default: {
                        dm_error("%s: DPCD DSC throughput mode not recognized.\n", __func__);
                        return false;
                }
        }

        return true;
}


static bool dsc_bpp_increment_div_from_dpcd(uint8_t bpp_increment_dpcd, uint32_t *bpp_increment_div)
{
        // Mask bpp increment dpcd field to avoid reading other fields
        bpp_increment_dpcd &= 0x7;

        switch (bpp_increment_dpcd) {
        case 0:
                *bpp_increment_div = 16;
                break;
        case 1:
                *bpp_increment_div = 8;
                break;
        case 2:
                *bpp_increment_div = 4;
                break;
        case 3:
                *bpp_increment_div = 2;
                break;
        case 4:
                *bpp_increment_div = 1;
                break;
        default: {
                dm_error("%s: DPCD DSC bits-per-pixel increment not recognized.\n", __func__);
                return false;
        }
        }

        return true;
}



bool dc_dsc_parse_dsc_dpcd(const struct dc *dc,
                const uint8_t *dpcd_dsc_basic_data,
                const uint8_t *dpcd_dsc_branch_decoder_caps,
                struct dsc_dec_dpcd_caps *dsc_sink_caps)
{
        if (!dpcd_dsc_basic_data)
                return false;

        dsc_sink_caps->is_dsc_supported =
                (dpcd_dsc_basic_data[DP_DSC_SUPPORT - DP_DSC_SUPPORT] & DP_DSC_DECOMPRESSION_IS_SUPPORTED) != 0;
        if (!dsc_sink_caps->is_dsc_supported)
                return false;

        dsc_sink_caps->dsc_version = dpcd_dsc_basic_data[DP_DSC_REV - DP_DSC_SUPPORT];

        {
                int buff_block_size;
                int buff_size;

                if (!dsc_buff_block_size_from_dpcd(dpcd_dsc_basic_data[DP_DSC_RC_BUF_BLK_SIZE - DP_DSC_SUPPORT],
                                                                                   &buff_block_size))
                        return false;

                buff_size = dpcd_dsc_basic_data[DP_DSC_RC_BUF_SIZE - DP_DSC_SUPPORT] + 1;
                dsc_sink_caps->rc_buffer_size = buff_size * buff_block_size;
        }

        dsc_sink_caps->slice_caps1.raw = dpcd_dsc_basic_data[DP_DSC_SLICE_CAP_1 - DP_DSC_SUPPORT];
        if (!dsc_line_buff_depth_from_dpcd(dpcd_dsc_basic_data[DP_DSC_LINE_BUF_BIT_DEPTH - DP_DSC_SUPPORT],
                                                                           &dsc_sink_caps->lb_bit_depth))
                return false;

        dsc_sink_caps->is_block_pred_supported =
                (dpcd_dsc_basic_data[DP_DSC_BLK_PREDICTION_SUPPORT - DP_DSC_SUPPORT] &
                 DP_DSC_BLK_PREDICTION_IS_SUPPORTED) != 0;

        dsc_sink_caps->edp_max_bits_per_pixel =
                dpcd_dsc_basic_data[DP_DSC_MAX_BITS_PER_PIXEL_LOW - DP_DSC_SUPPORT] |
                dpcd_dsc_basic_data[DP_DSC_MAX_BITS_PER_PIXEL_HI - DP_DSC_SUPPORT] << 8;

        dsc_sink_caps->color_formats.raw = dpcd_dsc_basic_data[DP_DSC_DEC_COLOR_FORMAT_CAP - DP_DSC_SUPPORT];
        dsc_sink_caps->color_depth.raw = dpcd_dsc_basic_data[DP_DSC_DEC_COLOR_DEPTH_CAP - DP_DSC_SUPPORT];

        {
                int dpcd_throughput = dpcd_dsc_basic_data[DP_DSC_PEAK_THROUGHPUT - DP_DSC_SUPPORT];

                if (!dsc_throughput_from_dpcd(dpcd_throughput & DP_DSC_THROUGHPUT_MODE_0_MASK,
                                                                          &dsc_sink_caps->throughput_mode_0_mps))
                        return false;

                dpcd_throughput = (dpcd_throughput & DP_DSC_THROUGHPUT_MODE_1_MASK) >> DP_DSC_THROUGHPUT_MODE_1_SHIFT;
                if (!dsc_throughput_from_dpcd(dpcd_throughput, &dsc_sink_caps->throughput_mode_1_mps))
                        return false;
        }

        dsc_sink_caps->max_slice_width = dpcd_dsc_basic_data[DP_DSC_MAX_SLICE_WIDTH - DP_DSC_SUPPORT] * 320;
        dsc_sink_caps->slice_caps2.raw = dpcd_dsc_basic_data[DP_DSC_SLICE_CAP_2 - DP_DSC_SUPPORT];

        if (!dsc_bpp_increment_div_from_dpcd(dpcd_dsc_basic_data[DP_DSC_BITS_PER_PIXEL_INC - DP_DSC_SUPPORT],
                                                                                 &dsc_sink_caps->bpp_increment_div))
                return false;

        if (dc->debug.dsc_bpp_increment_div) {
                /* dsc_bpp_increment_div should onl be 1, 2, 4, 8 or 16, but rather than rejecting invalid values,
                 * we'll accept all and get it into range. This also makes the above check against 0 redundant,
                 * but that one stresses out the override will be only used if it's not 0.
                 */
                if (dc->debug.dsc_bpp_increment_div >= 1)
                        dsc_sink_caps->bpp_increment_div = 1;
                if (dc->debug.dsc_bpp_increment_div >= 2)
                        dsc_sink_caps->bpp_increment_div = 2;
                if (dc->debug.dsc_bpp_increment_div >= 4)
                        dsc_sink_caps->bpp_increment_div = 4;
                if (dc->debug.dsc_bpp_increment_div >= 8)
                        dsc_sink_caps->bpp_increment_div = 8;
                if (dc->debug.dsc_bpp_increment_div >= 16)
                        dsc_sink_caps->bpp_increment_div = 16;
        }

        /* Extended caps */
        if (dpcd_dsc_branch_decoder_caps == NULL) { // branch decoder DPCD DSC data can be null for non branch device
                dsc_sink_caps->branch_overall_throughput_0_mps = 0;
                dsc_sink_caps->branch_overall_throughput_1_mps = 0;
                dsc_sink_caps->branch_max_line_width = 0;
                return true;
        }

        dsc_sink_caps->branch_overall_throughput_0_mps =
                dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_OVERALL_THROUGHPUT_0 - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0];
        if (dsc_sink_caps->branch_overall_throughput_0_mps == 0)
                dsc_sink_caps->branch_overall_throughput_0_mps = 0;
        else if (dsc_sink_caps->branch_overall_throughput_0_mps == 1)
                dsc_sink_caps->branch_overall_throughput_0_mps = 680;
        else {
                dsc_sink_caps->branch_overall_throughput_0_mps *= 50;
                dsc_sink_caps->branch_overall_throughput_0_mps += 600;
        }

        dsc_sink_caps->branch_overall_throughput_1_mps =
                dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_OVERALL_THROUGHPUT_1 - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0];
        if (dsc_sink_caps->branch_overall_throughput_1_mps == 0)
                dsc_sink_caps->branch_overall_throughput_1_mps = 0;
        else if (dsc_sink_caps->branch_overall_throughput_1_mps == 1)
                dsc_sink_caps->branch_overall_throughput_1_mps = 680;
        else {
                dsc_sink_caps->branch_overall_throughput_1_mps *= 50;
                dsc_sink_caps->branch_overall_throughput_1_mps += 600;
        }

        dsc_sink_caps->branch_max_line_width =
                dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_MAX_LINE_WIDTH - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0] * 320;
        ASSERT(dsc_sink_caps->branch_max_line_width == 0 || dsc_sink_caps->branch_max_line_width >= 5120);

        dsc_sink_caps->is_dp = true;
        return true;
}


/* If DSC is possbile, get DSC bandwidth range based on [min_bpp, max_bpp] target bitrate range and
 * timing's pixel clock and uncompressed bandwidth.
 * If DSC is not possible, leave '*range' untouched.
 */
bool dc_dsc_compute_bandwidth_range(
                const struct display_stream_compressor *dsc,
                uint32_t dsc_min_slice_height_override,
                uint32_t min_bpp_x16,
                uint32_t max_bpp_x16,
                const struct dsc_dec_dpcd_caps *dsc_sink_caps,
                const struct dc_crtc_timing *timing,
                struct dc_dsc_bw_range *range)
{
        bool is_dsc_possible = false;
        struct dsc_enc_caps dsc_enc_caps;
        struct dsc_enc_caps dsc_common_caps;
        struct dc_dsc_config config;

        get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);

        is_dsc_possible = intersect_dsc_caps(dsc_sink_caps, &dsc_enc_caps,
                        timing->pixel_encoding, &dsc_common_caps);

        if (is_dsc_possible)
                is_dsc_possible = setup_dsc_config(dsc_sink_caps, &dsc_enc_caps, 0, timing,
                                dsc_min_slice_height_override, max_bpp_x16, &config);

        if (is_dsc_possible)
                is_dsc_possible = decide_dsc_bandwidth_range(min_bpp_x16, max_bpp_x16,
                                config.num_slices_h, &dsc_common_caps, timing, range);

        return is_dsc_possible;
}

static void get_dsc_enc_caps(
                const struct display_stream_compressor *dsc,
                struct dsc_enc_caps *dsc_enc_caps,
                int pixel_clock_100Hz)
{
        // This is a static HW query, so we can use any DSC

        memset(dsc_enc_caps, 0, sizeof(struct dsc_enc_caps));
        if (dsc) {
                if (!dsc->ctx->dc->debug.disable_dsc)
                        dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, pixel_clock_100Hz);
                if (dsc->ctx->dc->debug.native422_support)
                        dsc_enc_caps->color_formats.bits.YCBCR_NATIVE_422 = 1;
        }
}

/* Returns 'false' if no intersection was found for at least one capability.
 * It also implicitly validates some sink caps against invalid value of zero.
 */
static bool intersect_dsc_caps(
                const struct dsc_dec_dpcd_caps *dsc_sink_caps,
                const struct dsc_enc_caps *dsc_enc_caps,
                enum dc_pixel_encoding pixel_encoding,
                struct dsc_enc_caps *dsc_common_caps)
{
        int32_t max_slices;
        int32_t total_sink_throughput;

        memset(dsc_common_caps, 0, sizeof(struct dsc_enc_caps));

        dsc_common_caps->dsc_version = min(dsc_sink_caps->dsc_version, dsc_enc_caps->dsc_version);
        if (!dsc_common_caps->dsc_version)
                return false;

        dsc_common_caps->slice_caps.bits.NUM_SLICES_1 =
                dsc_sink_caps->slice_caps1.bits.NUM_SLICES_1 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_1;
        dsc_common_caps->slice_caps.bits.NUM_SLICES_2 =
                dsc_sink_caps->slice_caps1.bits.NUM_SLICES_2 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_2;
        dsc_common_caps->slice_caps.bits.NUM_SLICES_4 =
                dsc_sink_caps->slice_caps1.bits.NUM_SLICES_4 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_4;
        dsc_common_caps->slice_caps.bits.NUM_SLICES_8 =
                dsc_sink_caps->slice_caps1.bits.NUM_SLICES_8 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_8;
        if (!dsc_common_caps->slice_caps.raw)
                return false;

        dsc_common_caps->lb_bit_depth = min(dsc_sink_caps->lb_bit_depth, dsc_enc_caps->lb_bit_depth);
        if (!dsc_common_caps->lb_bit_depth)
                return false;

        dsc_common_caps->is_block_pred_supported =
                dsc_sink_caps->is_block_pred_supported && dsc_enc_caps->is_block_pred_supported;

        dsc_common_caps->color_formats.raw = dsc_sink_caps->color_formats.raw & dsc_enc_caps->color_formats.raw;
        if (!dsc_common_caps->color_formats.raw)
                return false;

        dsc_common_caps->color_depth.raw = dsc_sink_caps->color_depth.raw & dsc_enc_caps->color_depth.raw;
        if (!dsc_common_caps->color_depth.raw)
                return false;

        max_slices = 0;
        if (dsc_common_caps->slice_caps.bits.NUM_SLICES_1)
                max_slices = 1;

        if (dsc_common_caps->slice_caps.bits.NUM_SLICES_2)
                max_slices = 2;

        if (dsc_common_caps->slice_caps.bits.NUM_SLICES_4)
                max_slices = 4;

        total_sink_throughput = max_slices * dsc_sink_caps->throughput_mode_0_mps;
        if (pixel_encoding == PIXEL_ENCODING_YCBCR422 || pixel_encoding == PIXEL_ENCODING_YCBCR420)
                total_sink_throughput = max_slices * dsc_sink_caps->throughput_mode_1_mps;

        dsc_common_caps->max_total_throughput_mps = min(total_sink_throughput, dsc_enc_caps->max_total_throughput_mps);

        dsc_common_caps->max_slice_width = min(dsc_sink_caps->max_slice_width, dsc_enc_caps->max_slice_width);
        if (!dsc_common_caps->max_slice_width)
                return false;

        dsc_common_caps->bpp_increment_div = min(dsc_sink_caps->bpp_increment_div, dsc_enc_caps->bpp_increment_div);

        // TODO DSC: Remove this workaround for N422 and 420 once it's fixed, or move it to get_dsc_encoder_caps()
        if (pixel_encoding == PIXEL_ENCODING_YCBCR422 || pixel_encoding == PIXEL_ENCODING_YCBCR420)
                dsc_common_caps->bpp_increment_div = min(dsc_common_caps->bpp_increment_div, (uint32_t)8);

        dsc_common_caps->edp_sink_max_bits_per_pixel = dsc_sink_caps->edp_max_bits_per_pixel;
        dsc_common_caps->is_dp = dsc_sink_caps->is_dp;
        return true;
}

static inline uint32_t dsc_div_by_10_round_up(uint32_t value)
{
        return (value + 9) / 10;
}

static uint32_t compute_bpp_x16_from_target_bandwidth(
        const uint32_t bandwidth_in_kbps,
        const struct dc_crtc_timing *timing,
        const uint32_t num_slices_h,
        const uint32_t bpp_increment_div,
        const bool is_dp)
{
        uint32_t overhead_in_kbps;
        struct fixed31_32 effective_bandwidth_in_kbps;
        struct fixed31_32 bpp_x16;

        overhead_in_kbps = dc_dsc_stream_bandwidth_overhead_in_kbps(
                                timing, num_slices_h, is_dp);
        effective_bandwidth_in_kbps = dc_fixpt_from_int(bandwidth_in_kbps);
        effective_bandwidth_in_kbps = dc_fixpt_sub_int(effective_bandwidth_in_kbps,
                        overhead_in_kbps);
        bpp_x16 = dc_fixpt_mul_int(effective_bandwidth_in_kbps, 10);
        bpp_x16 = dc_fixpt_div_int(bpp_x16, timing->pix_clk_100hz);
        bpp_x16 = dc_fixpt_from_int(dc_fixpt_floor(dc_fixpt_mul_int(bpp_x16, bpp_increment_div)));
        bpp_x16 = dc_fixpt_div_int(bpp_x16, bpp_increment_div);
        bpp_x16 = dc_fixpt_mul_int(bpp_x16, 16);
        return dc_fixpt_floor(bpp_x16);
}

/* Decide DSC bandwidth range based on signal, timing, specs specific and input min and max
 * requirements.
 * The range output includes decided min/max target bpp, the respective bandwidth requirements
 * and native timing bandwidth requirement when DSC is not used.
 */
static bool decide_dsc_bandwidth_range(
                const uint32_t min_bpp_x16,
                const uint32_t max_bpp_x16,
                const uint32_t num_slices_h,
                const struct dsc_enc_caps *dsc_caps,
                const struct dc_crtc_timing *timing,
                struct dc_dsc_bw_range *range)
{
        uint32_t preferred_bpp_x16 = timing->dsc_fixed_bits_per_pixel_x16;

        memset(range, 0, sizeof(*range));

        /* apply signal, timing, specs and explicitly specified DSC range requirements */
        if (preferred_bpp_x16) {
                if (preferred_bpp_x16 <= max_bpp_x16 &&
                                preferred_bpp_x16 >= min_bpp_x16) {
                        range->max_target_bpp_x16 = preferred_bpp_x16;
                        range->min_target_bpp_x16 = preferred_bpp_x16;
                }
        }
        /* TODO - make this value generic to all signal types */
        else if (dsc_caps->edp_sink_max_bits_per_pixel) {
                /* apply max bpp limitation from edp sink */
                range->max_target_bpp_x16 = MIN(dsc_caps->edp_sink_max_bits_per_pixel,
                                max_bpp_x16);
                range->min_target_bpp_x16 = min_bpp_x16;
        }
        else {
                range->max_target_bpp_x16 = max_bpp_x16;
                range->min_target_bpp_x16 = min_bpp_x16;
        }

        /* populate output structure */
        if (range->max_target_bpp_x16 >= range->min_target_bpp_x16 && range->min_target_bpp_x16 > 0) {
                /* native stream bandwidth */
                range->stream_kbps = dc_bandwidth_in_kbps_from_timing(timing);

                /* max dsc target bpp */
                range->max_kbps = dc_dsc_stream_bandwidth_in_kbps(timing,
                                range->max_target_bpp_x16, num_slices_h, dsc_caps->is_dp);

                /* min dsc target bpp */
                range->min_kbps = dc_dsc_stream_bandwidth_in_kbps(timing,
                                range->min_target_bpp_x16, num_slices_h, dsc_caps->is_dp);
        }

        return range->max_kbps >= range->min_kbps && range->min_kbps > 0;
}

/* Decides if DSC should be used and calculates target bpp if it should, applying DSC policy.
 *
 * Returns:
 *     - 'true' if target bpp is decided
 *     - 'false' if target bpp cannot be decided (e.g. cannot fit even with min DSC bpp),
 */
static bool decide_dsc_target_bpp_x16(
                const struct dc_dsc_policy *policy,
                const struct dsc_enc_caps *dsc_common_caps,
                const int target_bandwidth_kbps,
                const struct dc_crtc_timing *timing,
                const int num_slices_h,
                int *target_bpp_x16)
{
        struct dc_dsc_bw_range range;

        *target_bpp_x16 = 0;

        if (decide_dsc_bandwidth_range(policy->min_target_bpp * 16, policy->max_target_bpp * 16,
                        num_slices_h, dsc_common_caps, timing, &range)) {
                if (target_bandwidth_kbps >= range.stream_kbps) {
                        if (policy->enable_dsc_when_not_needed)
                                /* enable max bpp even dsc is not needed */
                                *target_bpp_x16 = range.max_target_bpp_x16;
                } else if (target_bandwidth_kbps >= range.max_kbps) {
                        /* use max target bpp allowed */
                        *target_bpp_x16 = range.max_target_bpp_x16;
                } else if (target_bandwidth_kbps >= range.min_kbps) {
                        /* use target bpp that can take entire target bandwidth */
                        *target_bpp_x16 = compute_bpp_x16_from_target_bandwidth(
                                        target_bandwidth_kbps, timing, num_slices_h,
                                        dsc_common_caps->bpp_increment_div,
                                        dsc_common_caps->is_dp);
                }
        }

        return *target_bpp_x16 != 0;
}

#define MIN_AVAILABLE_SLICES_SIZE  6

static int get_available_dsc_slices(union dsc_enc_slice_caps slice_caps, int *available_slices)
{
        int idx = 0;

        memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE);

        if (slice_caps.bits.NUM_SLICES_1)
                available_slices[idx++] = 1;

        if (slice_caps.bits.NUM_SLICES_2)
                available_slices[idx++] = 2;

        if (slice_caps.bits.NUM_SLICES_4)
                available_slices[idx++] = 4;

        if (slice_caps.bits.NUM_SLICES_8)
                available_slices[idx++] = 8;

        return idx;
}


static int get_max_dsc_slices(union dsc_enc_slice_caps slice_caps)
{
        int max_slices = 0;
        int available_slices[MIN_AVAILABLE_SLICES_SIZE];
        int end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);

        if (end_idx > 0)
                max_slices = available_slices[end_idx - 1];

        return max_slices;
}


// Increment sice number in available sice numbers stops if possible, or just increment if not
static int inc_num_slices(union dsc_enc_slice_caps slice_caps, int num_slices)
{
        // Get next bigger num slices available in common caps
        int available_slices[MIN_AVAILABLE_SLICES_SIZE];
        int end_idx;
        int i;
        int new_num_slices = num_slices;

        end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);
        if (end_idx == 0) {
                // No available slices found
                new_num_slices++;
                return new_num_slices;
        }

        // Numbers of slices found - get the next bigger number
        for (i = 0; i < end_idx; i++) {
                if (new_num_slices < available_slices[i]) {
                        new_num_slices = available_slices[i];
                        break;
                }
        }

        if (new_num_slices == num_slices) // No biger number of slices found
                new_num_slices++;

        return new_num_slices;
}


// Decrement sice number in available sice numbers stops if possible, or just decrement if not. Stop at zero.
static int dec_num_slices(union dsc_enc_slice_caps slice_caps, int num_slices)
{
        // Get next bigger num slices available in common caps
        int available_slices[MIN_AVAILABLE_SLICES_SIZE];
        int end_idx;
        int i;
        int new_num_slices = num_slices;

        end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);
        if (end_idx == 0 && new_num_slices > 0) {
                // No numbers of slices found
                new_num_slices++;
                return new_num_slices;
        }

        // Numbers of slices found - get the next smaller number
        for (i = end_idx - 1; i >= 0; i--) {
                if (new_num_slices > available_slices[i]) {
                        new_num_slices = available_slices[i];
                        break;
                }
        }

        if (new_num_slices == num_slices) {
                // No smaller number of slices found
                new_num_slices--;
                if (new_num_slices < 0)
                        new_num_slices = 0;
        }

        return new_num_slices;
}


// Choose next bigger number of slices if the requested number of slices is not available
static int fit_num_slices_up(union dsc_enc_slice_caps slice_caps, int num_slices)
{
        // Get next bigger num slices available in common caps
        int available_slices[MIN_AVAILABLE_SLICES_SIZE];
        int end_idx;
        int i;
        int new_num_slices = num_slices;

        end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);
        if (end_idx == 0) {
                // No available slices found
                new_num_slices++;
                return new_num_slices;
        }

        // Numbers of slices found - get the equal or next bigger number
        for (i = 0; i < end_idx; i++) {
                if (new_num_slices <= available_slices[i]) {
                        new_num_slices = available_slices[i];
                        break;
                }
        }

        return new_num_slices;
}


/* Attempts to set DSC configuration for the stream, applying DSC policy.
 * Returns 'true' if successful or 'false' if not.
 *
 * Parameters:
 *
 * dsc_sink_caps       - DSC sink decoder capabilities (from DPCD)
 *
 * dsc_enc_caps        - DSC encoder capabilities
 *
 * target_bandwidth_kbps  - Target bandwidth to fit the stream into.
 *                          If 0, do not calculate target bpp.
 *
 * timing              - The stream timing to fit into 'target_bandwidth_kbps' or apply
 *                       maximum compression to, if 'target_badwidth == 0'
 *
 * dsc_cfg             - DSC configuration to use if it was possible to come up with
 *                       one for the given inputs.
 *                       The target bitrate after DSC can be calculated by multiplying
 *                       dsc_cfg.bits_per_pixel (in U6.4 format) by pixel rate, e.g.
 *
 *                       dsc_stream_bitrate_kbps = (int)ceil(timing->pix_clk_khz * dsc_cfg.bits_per_pixel / 16.0);
 */
static bool setup_dsc_config(
                const struct dsc_dec_dpcd_caps *dsc_sink_caps,
                const struct dsc_enc_caps *dsc_enc_caps,
                int target_bandwidth_kbps,
                const struct dc_crtc_timing *timing,
                int min_slice_height_override,
                int max_dsc_target_bpp_limit_override_x16,
                struct dc_dsc_config *dsc_cfg)
{
        struct dsc_enc_caps dsc_common_caps;
        int max_slices_h;
        int min_slices_h;
        int num_slices_h;
        int pic_width;
        int slice_width;
        int target_bpp;
        int sink_per_slice_throughput_mps;
        int branch_max_throughput_mps = 0;
        bool is_dsc_possible = false;
        int pic_height;
        int slice_height;
        struct dc_dsc_policy policy;

        memset(dsc_cfg, 0, sizeof(struct dc_dsc_config));

        dc_dsc_get_policy_for_timing(timing, max_dsc_target_bpp_limit_override_x16, &policy);
        pic_width = timing->h_addressable + timing->h_border_left + timing->h_border_right;
        pic_height = timing->v_addressable + timing->v_border_top + timing->v_border_bottom;

        if (!dsc_sink_caps->is_dsc_supported)
                goto done;

        if (dsc_sink_caps->branch_max_line_width && dsc_sink_caps->branch_max_line_width < pic_width)
                goto done;

        // Intersect decoder with encoder DSC caps and validate DSC settings
        is_dsc_possible = intersect_dsc_caps(dsc_sink_caps, dsc_enc_caps, timing->pixel_encoding, &dsc_common_caps);
        if (!is_dsc_possible)
                goto done;

        sink_per_slice_throughput_mps = 0;

        // Validate available DSC settings against the mode timing

        // Validate color format (and pick up the throughput values)
        dsc_cfg->ycbcr422_simple = false;
        switch (timing->pixel_encoding) {
        case PIXEL_ENCODING_RGB:
                is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.RGB;
                sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_0_mps;
                branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_0_mps;
                break;
        case PIXEL_ENCODING_YCBCR444:
                is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_444;
                sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_0_mps;
                branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_0_mps;
                break;
        case PIXEL_ENCODING_YCBCR422:
                is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_NATIVE_422;
                sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_1_mps;
                branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_1_mps;
                if (!is_dsc_possible) {
                        is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_SIMPLE_422;
                        dsc_cfg->ycbcr422_simple = is_dsc_possible;
                        sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_0_mps;
                }
                break;
        case PIXEL_ENCODING_YCBCR420:
                is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_NATIVE_420;
                sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_1_mps;
                branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_1_mps;
                break;
        default:
                is_dsc_possible = false;
        }

        // Validate branch's maximum throughput
        if (branch_max_throughput_mps && dsc_div_by_10_round_up(timing->pix_clk_100hz) > branch_max_throughput_mps * 1000)
                is_dsc_possible = false;

        if (!is_dsc_possible)
                goto done;

        // Color depth
        switch (timing->display_color_depth) {
        case COLOR_DEPTH_888:
                is_dsc_possible = (bool)dsc_common_caps.color_depth.bits.COLOR_DEPTH_8_BPC;
                break;
        case COLOR_DEPTH_101010:
                is_dsc_possible = (bool)dsc_common_caps.color_depth.bits.COLOR_DEPTH_10_BPC;
                break;
        case COLOR_DEPTH_121212:
                is_dsc_possible = (bool)dsc_common_caps.color_depth.bits.COLOR_DEPTH_12_BPC;
                break;
        default:
                is_dsc_possible = false;
        }

        if (!is_dsc_possible)
                goto done;

        // Slice width (i.e. number of slices per line)
        max_slices_h = get_max_dsc_slices(dsc_common_caps.slice_caps);

        while (max_slices_h > 0) {
                if (pic_width % max_slices_h == 0)
                        break;

                max_slices_h = dec_num_slices(dsc_common_caps.slice_caps, max_slices_h);
        }

        is_dsc_possible = (dsc_common_caps.max_slice_width > 0);
        if (!is_dsc_possible)
                goto done;

        min_slices_h = pic_width / dsc_common_caps.max_slice_width;
        if (pic_width % dsc_common_caps.max_slice_width)
                min_slices_h++;

        min_slices_h = fit_num_slices_up(dsc_common_caps.slice_caps, min_slices_h);

        while (min_slices_h <= max_slices_h) {
                int pix_clk_per_slice_khz = dsc_div_by_10_round_up(timing->pix_clk_100hz) / min_slices_h;
                if (pix_clk_per_slice_khz <= sink_per_slice_throughput_mps * 1000)
                        break;

                min_slices_h = inc_num_slices(dsc_common_caps.slice_caps, min_slices_h);
        }

        is_dsc_possible = (min_slices_h <= max_slices_h);

        if (pic_width % min_slices_h != 0)
                min_slices_h = 0; // DSC TODO: Maybe try increasing the number of slices first?

        if (min_slices_h == 0 && max_slices_h == 0)
                is_dsc_possible = false;

        if (!is_dsc_possible)
                goto done;

        if (policy.use_min_slices_h) {
                if (min_slices_h > 0)
                        num_slices_h = min_slices_h;
                else if (max_slices_h > 0) { // Fall back to max slices if min slices is not working out
                        if (policy.max_slices_h)
                                num_slices_h = min(policy.max_slices_h, max_slices_h);
                        else
                                num_slices_h = max_slices_h;
                } else
                        is_dsc_possible = false;
        } else {
                if (max_slices_h > 0) {
                        if (policy.max_slices_h)
                                num_slices_h = min(policy.max_slices_h, max_slices_h);
                        else
                                num_slices_h = max_slices_h;
                } else if (min_slices_h > 0) // Fall back to min slices if max slices is not possible
                        num_slices_h = min_slices_h;
                else
                        is_dsc_possible = false;
        }

        if (!is_dsc_possible)
                goto done;

        dsc_cfg->num_slices_h = num_slices_h;
        slice_width = pic_width / num_slices_h;

        is_dsc_possible = slice_width <= dsc_common_caps.max_slice_width;
        if (!is_dsc_possible)
                goto done;

        // Slice height (i.e. number of slices per column): start with policy and pick the first one that height is divisible by.
        // For 4:2:0 make sure the slice height is divisible by 2 as well.
        if (min_slice_height_override == 0)
                slice_height = min(policy.min_slice_height, pic_height);
        else
                slice_height = min(min_slice_height_override, pic_height);

        while (slice_height < pic_height && (pic_height % slice_height != 0 ||
                (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420 && slice_height % 2 != 0)))
                slice_height++;

        if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420) // For the case when pic_height < dsc_policy.min_sice_height
                is_dsc_possible = (slice_height % 2 == 0);

        if (!is_dsc_possible)
                goto done;

        dsc_cfg->num_slices_v = pic_height/slice_height;

        if (target_bandwidth_kbps > 0) {
                is_dsc_possible = decide_dsc_target_bpp_x16(
                                &policy,
                                &dsc_common_caps,
                                target_bandwidth_kbps,
                                timing,
                                num_slices_h,
                                &target_bpp);
                dsc_cfg->bits_per_pixel = target_bpp;
        }
        if (!is_dsc_possible)
                goto done;

        // Final decission: can we do DSC or not?
        if (is_dsc_possible) {
                // Fill out the rest of DSC settings
                dsc_cfg->block_pred_enable = dsc_common_caps.is_block_pred_supported;
                dsc_cfg->linebuf_depth = dsc_common_caps.lb_bit_depth;
                dsc_cfg->version_minor = (dsc_common_caps.dsc_version & 0xf0) >> 4;
                dsc_cfg->is_dp = dsc_sink_caps->is_dp;
        }

done:
        if (!is_dsc_possible)
                memset(dsc_cfg, 0, sizeof(struct dc_dsc_config));

        return is_dsc_possible;
}

bool dc_dsc_compute_config(
                const struct display_stream_compressor *dsc,
                const struct dsc_dec_dpcd_caps *dsc_sink_caps,
                uint32_t dsc_min_slice_height_override,
                uint32_t max_target_bpp_limit_override,
                uint32_t target_bandwidth_kbps,
                const struct dc_crtc_timing *timing,
                struct dc_dsc_config *dsc_cfg)
{
        bool is_dsc_possible = false;
        struct dsc_enc_caps dsc_enc_caps;

        get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);
        is_dsc_possible = setup_dsc_config(dsc_sink_caps,
                &dsc_enc_caps,
                target_bandwidth_kbps,
                timing, dsc_min_slice_height_override,
                max_target_bpp_limit_override * 16, dsc_cfg);
        return is_dsc_possible;
}

uint32_t dc_dsc_stream_bandwidth_in_kbps(const struct dc_crtc_timing *timing,
        uint32_t bpp_x16, uint32_t num_slices_h, bool is_dp)
{
        uint32_t overhead_in_kbps;
        struct fixed31_32 bpp;
        struct fixed31_32 actual_bandwidth_in_kbps;

        overhead_in_kbps = dc_dsc_stream_bandwidth_overhead_in_kbps(
                timing, num_slices_h, is_dp);
        bpp = dc_fixpt_from_fraction(bpp_x16, 16);
        actual_bandwidth_in_kbps = dc_fixpt_from_fraction(timing->pix_clk_100hz, 10);
        actual_bandwidth_in_kbps = dc_fixpt_mul(actual_bandwidth_in_kbps, bpp);
        actual_bandwidth_in_kbps = dc_fixpt_add_int(actual_bandwidth_in_kbps, overhead_in_kbps);
        return dc_fixpt_ceil(actual_bandwidth_in_kbps);
}

uint32_t dc_dsc_stream_bandwidth_overhead_in_kbps(
                const struct dc_crtc_timing *timing,
                const int num_slices_h,
                const bool is_dp)
{
        struct fixed31_32 max_dsc_overhead;

        struct fixed31_32 refresh_rate;

        if (dsc_policy_disable_dsc_stream_overhead || !is_dp)
                return 0;

        /* use target bpp that can take entire target bandwidth */
        refresh_rate = dc_fixpt_from_int(timing->pix_clk_100hz);
        refresh_rate = dc_fixpt_div_int(refresh_rate, timing->h_total);
        refresh_rate = dc_fixpt_div_int(refresh_rate, timing->v_total);
        refresh_rate = dc_fixpt_mul_int(refresh_rate, 100);

        max_dsc_overhead = dc_fixpt_from_int(num_slices_h);
        max_dsc_overhead = dc_fixpt_mul_int(max_dsc_overhead, timing->v_total);
        max_dsc_overhead = dc_fixpt_mul_int(max_dsc_overhead, 256);
        max_dsc_overhead = dc_fixpt_div_int(max_dsc_overhead, 1000);
        max_dsc_overhead = dc_fixpt_mul(max_dsc_overhead, refresh_rate);

        return dc_fixpt_ceil(max_dsc_overhead);
}

void dc_dsc_get_policy_for_timing(const struct dc_crtc_timing *timing,
                uint32_t max_target_bpp_limit_override_x16,
                struct dc_dsc_policy *policy)
{
        uint32_t bpc = 0;

        policy->min_target_bpp = 0;
        policy->max_target_bpp = 0;

        /* DSC Policy: Use minimum number of slices that fits the pixel clock */
        policy->use_min_slices_h = true;

        /* DSC Policy: Use max available slices
         * (in our case 4 for or 8, depending on the mode)
         */
        policy->max_slices_h = 0;

        /* DSC Policy: Use slice height recommended
         * by VESA DSC Spreadsheet user guide
         */
        policy->min_slice_height = 108;

        /* DSC Policy: follow DP specs with an internal upper limit to 16 bpp
         * for better interoperability
         */
        switch (timing->display_color_depth) {
        case COLOR_DEPTH_888:
                bpc = 8;
                break;
        case COLOR_DEPTH_101010:
                bpc = 10;
                break;
        case COLOR_DEPTH_121212:
                bpc = 12;
                break;
        default:
                return;
        }
        switch (timing->pixel_encoding) {
        case PIXEL_ENCODING_RGB:
        case PIXEL_ENCODING_YCBCR444:
        case PIXEL_ENCODING_YCBCR422: /* assume no YCbCr422 native support */
                /* DP specs limits to 8 */
                policy->min_target_bpp = 8;
                /* DP specs limits to 3 x bpc */
                policy->max_target_bpp = 3 * bpc;
                break;
        case PIXEL_ENCODING_YCBCR420:
                /* DP specs limits to 6 */
                policy->min_target_bpp = 6;
                /* DP specs limits to 1.5 x bpc assume bpc is an even number */
                policy->max_target_bpp = bpc * 3 / 2;
                break;
        default:
                return;
        }

        /* internal upper limit, default 16 bpp */
        if (policy->max_target_bpp > dsc_policy_max_target_bpp_limit)
                policy->max_target_bpp = dsc_policy_max_target_bpp_limit;

        /* apply override */
        if (max_target_bpp_limit_override_x16 && policy->max_target_bpp > max_target_bpp_limit_override_x16 / 16)
                policy->max_target_bpp = max_target_bpp_limit_override_x16 / 16;

        /* enable DSC when not needed, default false */
        if (dsc_policy_enable_dsc_when_not_needed)
                policy->enable_dsc_when_not_needed = dsc_policy_enable_dsc_when_not_needed;
        else
                policy->enable_dsc_when_not_needed = false;
}

void dc_dsc_policy_set_max_target_bpp_limit(uint32_t limit)
{
        dsc_policy_max_target_bpp_limit = limit;
}

void dc_dsc_policy_set_enable_dsc_when_not_needed(bool enable)
{
        dsc_policy_enable_dsc_when_not_needed = enable;
}

void dc_dsc_policy_set_disable_dsc_stream_overhead(bool disable)
{
        dsc_policy_disable_dsc_stream_overhead = disable;
}