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-rw-r--r--arch/arm/include/asm/arch-tegra/tegra_mmc.h2
-rw-r--r--drivers/mmc/Kconfig8
-rw-r--r--drivers/mmc/tegra_mmc.c13
3 files changed, 23 insertions, 0 deletions
diff --git a/arch/arm/include/asm/arch-tegra/tegra_mmc.h b/arch/arm/include/asm/arch-tegra/tegra_mmc.h
index 64c848acb1..c40599ab19 100644
--- a/arch/arm/include/asm/arch-tegra/tegra_mmc.h
+++ b/arch/arm/include/asm/arch-tegra/tegra_mmc.h
@@ -108,6 +108,8 @@ struct tegra_mmc {
#define TEGRA_MMC_CLKCON_SDCLK_FREQ_SEL_SHIFT 8
#define TEGRA_MMC_CLKCON_SDCLK_FREQ_SEL_MASK (0xff << 8)
+#define TEGRA_MMC_MISCON_ENABLE_EXT_LOOPBACK (1 << 17)
+
#define TEGRA_MMC_SWRST_SW_RESET_FOR_ALL (1 << 0)
#define TEGRA_MMC_SWRST_SW_RESET_FOR_CMD_LINE (1 << 1)
#define TEGRA_MMC_SWRST_SW_RESET_FOR_DAT_LINE (1 << 2)
diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index 19e89abc45..2c71420650 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -101,4 +101,12 @@ config TEGRA_MMC
help
This selects support for SDHCI on Tegra SoCs.
+config TEGRA124_MMC_DISABLE_EXT_LOOPBACK
+ bool "Disable external clock loopback"
+ depends on TEGRA_MMC && TEGRA124
+ help
+ Disable the external clock loopback and use the internal one on SDMMC3
+ as per the SDMMC_VENDOR_MISC_CNTRL_0 register's SDMMC_SPARE1 bits
+ being set to 0xfffd according to the TRM.
+
endmenu
diff --git a/drivers/mmc/tegra_mmc.c b/drivers/mmc/tegra_mmc.c
index 97b1154595..ed02708e9c 100644
--- a/drivers/mmc/tegra_mmc.c
+++ b/drivers/mmc/tegra_mmc.c
@@ -511,6 +511,19 @@ static int tegra_mmc_init(struct mmc *mmc)
tegra_mmc_reset(priv, mmc);
+#if defined(CONFIG_TEGRA124_MMC_DISABLE_EXT_LOOPBACK)
+ /*
+ * Disable the external clock loopback and use the internal one on
+ * SDMMC3 as per the SDMMC_VENDOR_MISC_CNTRL_0 register's SDMMC_SPARE1
+ * bits being set to 0xfffd according to the TRM.
+ */
+ if (priv->reg == (void *)0x700b0400) {
+ mask = readl(&priv->reg->venmiscctl);
+ mask &= ~TEGRA_MMC_MISCON_ENABLE_EXT_LOOPBACK;
+ writel(mask, &priv->reg->venmiscctl);
+ }
+#endif
+
priv->version = readw(&priv->reg->hcver);
debug("host version = %x\n", priv->version);