Extern or forward variable declaration at include/linux/mmc/host.h, line 474 References: arch/arm/mach-integrator/integrator_cp.c, line 122 arch/arm/mach-versatile/versatile_dt.c, line 129 arch/arm/mach-versatile/versatile_dt.c, line 165 drivers/mmc/host/dw_mmc-exynos.c, line 339 drivers/mmc/host/dw_mmc-rockchip.c, line 263 drivers/mmc/host/dw_mmc-zx.c, line 154 drivers/mmc/host/dw_mmc-zx.c, line 155 drivers/mmc/host/of_mmc_spi.c, line 58 drivers/mmc/host/of_mmc_spi.c, line 90 drivers/mmc/host/sdhci-pxav2.c, line 124 drivers/mmc/host/sdhci-st.c, line 142 drivers/mmc/host/sdhci-st.c, line 344 drivers/mmc/host/sdhci-st.c, line 488 drivers/mmc/host/sdhci-xenon-phy.c, line 651 drivers/mmc/host/sdhci-xenon-phy.c, line 693 drivers/mmc/host/sdhci-xenon-phy.c, line 814 drivers/mmc/host/sdhci-xenon-phy.c, line 836 drivers/mmc/host/wmt-sdmmc.c, line 753