LXR linux/drivers/gpu/drm/amd/amdgpu/amdgpu

   1/*
   2 * Copyright 2008 Advanced Micro Devices, Inc.
   3 * Copyright 2008 Red Hat Inc.
   4 * Copyright 2009 Christian König.
   5 *
   6 * Permission is hereby granted, free of charge, to any person obtaining a
   7 * copy of this software and associated documentation files (the "Software"),
   8 * to deal in the Software without restriction, including without limitation
   9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10 * and/or sell copies of the Software, and to permit persons to whom the
  11 * Software is furnished to do so, subject to the following conditions:
  12 *
  13 * The above copyright notice and this permission notice shall be included in
  14 * all copies or substantial portions of the Software.
  15 *
  16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22 * OTHER DEALINGS IN THE SOFTWARE.
  23 *
  24 * Authors: Christian König
  25 */
  26#include <linux/hdmi.h>
  27#include <linux/gcd.h>
  28#include <drm/drmP.h>
  29#include <drm/amdgpu_drm.h>
  30#include "amdgpu.h"
  31
  32static const struct amdgpu_afmt_acr amdgpu_afmt_predefined_acr[] = {
  33    /*       32kHz        44.1kHz       48kHz    */
  34    /* Clock      N     CTS      N     CTS      N     CTS */
  35    {  25175,  4096,  25175, 28224, 125875,  6144,  25175 }, /*  25,20/1.001 MHz */
  36    {  25200,  4096,  25200,  6272,  28000,  6144,  25200 }, /*  25.20       MHz */
  37    {  27000,  4096,  27000,  6272,  30000,  6144,  27000 }, /*  27.00       MHz */
  38    {  27027,  4096,  27027,  6272,  30030,  6144,  27027 }, /*  27.00*1.001 MHz */
  39    {  54000,  4096,  54000,  6272,  60000,  6144,  54000 }, /*  54.00       MHz */
  40    {  54054,  4096,  54054,  6272,  60060,  6144,  54054 }, /*  54.00*1.001 MHz */
  41    {  74176,  4096,  74176,  5733,  75335,  6144,  74176 }, /*  74.25/1.001 MHz */
  42    {  74250,  4096,  74250,  6272,  82500,  6144,  74250 }, /*  74.25       MHz */
  43    { 148352,  4096, 148352,  5733, 150670,  6144, 148352 }, /* 148.50/1.001 MHz */
  44    { 148500,  4096, 148500,  6272, 165000,  6144, 148500 }, /* 148.50       MHz */
  45};
  46
  47
  48/*
  49 * calculate CTS and N values if they are not found in the table
  50 */
  51static void amdgpu_afmt_calc_cts(uint32_t clock, int *CTS, int *N, int freq)
  52{
  53        int n, cts;
  54        unsigned long div, mul;
  55
  56        /* Safe, but overly large values */
  57        n = 128 * freq;
  58        cts = clock * 1000;
  59
  60        /* Smallest valid fraction */
  61        div = gcd(n, cts);
  62
  63        n /= div;
  64        cts /= div;
  65
  66        /*
  67         * The optimal N is 128*freq/1000. Calculate the closest larger
  68         * value that doesn't truncate any bits.
  69         */
  70        mul = ((128*freq/1000) + (n-1))/n;
  71
  72        n *= mul;
  73        cts *= mul;
  74
  75        /* Check that we are in spec (not always possible) */
  76        if (n < (128*freq/1500))
  77                printk(KERN_WARNING "Calculated ACR N value is too small. You may experience audio problems.\n");
  78        if (n > (128*freq/300))
  79                printk(KERN_WARNING "Calculated ACR N value is too large. You may experience audio problems.\n");
  80
  81        *N = n;
  82        *CTS = cts;
  83
  84        DRM_DEBUG("Calculated ACR timing N=%d CTS=%d for frequency %d\n",
  85                  *N, *CTS, freq);
  86}
  87
  88struct amdgpu_afmt_acr amdgpu_afmt_acr(uint32_t clock)
  89{
  90        struct amdgpu_afmt_acr res;
  91        u8 i;
  92
  93        /* Precalculated values for common clocks */
  94        for (i = 0; i < ARRAY_SIZE(amdgpu_afmt_predefined_acr); i++) {
  95                if (amdgpu_afmt_predefined_acr[i].clock == clock)
  96                        return amdgpu_afmt_predefined_acr[i];
  97        }
  98
  99        /* And odd clocks get manually calculated */
 100        amdgpu_afmt_calc_cts(clock, &res.cts_32khz, &res.n_32khz, 32000);
 101        amdgpu_afmt_calc_cts(clock, &res.cts_44_1khz, &res.n_44_1khz, 44100);
 102        amdgpu_afmt_calc_cts(clock, &res.cts_48khz, &res.n_48khz, 48000);
 103
 104        return res;
 105}
 106