From: Marcel Ziswiler <marcel.ziswi...@toradex.com>
Introduce CONFIG_TEGRA124_MMC_DISABLE_EXT_LOOPBACK to 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.
Signed-off-by: Marcel Ziswiler <marcel.ziswi...@toradex.com>
Reviewed-by: Simon Glass <s...@chromium.org>
---
Changes in v3: None
Changes in v2:
- Added Simon's reviewed-by.
- Added TODO(email) as suggested by Simon so it is clear this is
temporary and will be moved to device tree controlled approach once
proper kernel integration made it mainline.
arch/arm/include/asm/arch-tegra/tegra_mmc.h | 2 ++
drivers/mmc/Kconfig | 11 +++++++++++
drivers/mmc/tegra_mmc.c | 16 ++++++++++++++++
3 files changed, 29 insertions(+)
diff --git a/arch/arm/include/asm/arch-tegra/tegra_mmc.h
b/arch/arm/include/asm/arch-tegra/tegra_mmc.h
index 64c848a..c40599a 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 18f0e97..6372876 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -116,4 +116,15 @@ 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.
+
+ TODO(marcel.ziswi...@toradex.com): Move to device tree controlled
+ approach once proper kernel integration made it mainline.
+
endmenu
diff --git a/drivers/mmc/tegra_mmc.c b/drivers/mmc/tegra_mmc.c
index 97b1154..839b15d 100644
--- a/drivers/mmc/tegra_mmc.c
+++ b/drivers/mmc/tegra_mmc.c
@@ -511,6 +511,22 @@ 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.
+ *
+ * TODO(marcel.ziswi...@toradex.com): Move to device tree controlled
+ * approach once proper kernel integration made it mainline.
+ */
+ 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);
--
2.9.3
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