[PATCH] mmc: meson-gx: change clock phase value on AGX SoCs

[Stefan Agner]

Amlogic AGX SoCs seem to have issue communicating with some eMMC
devices (in particular with a Micron 128GB eMMC 5.1). The device
is detected with 1-bit bus width, and at higher temperature loading
pretty much anything from the storage fails: (e.g. fs_devread read error
- block).

When phase is set to 270° it is detected with 8-bit bus width and is
working fine accross all temperatures.

Signed-off-by: Stefan Agner <stefan at agner.ch>
---
Hi Neil,

I debugged this issue today on an ODROID N2+ not booting reliably. I am
not sure if we can safely switch to 270° for all SoCs with
amlogic,meson-axg-mmc, but I guess we have to try and see what happens?
I will do a bit broader testing in the comming days here.

Btw, I do see that 180° is also set in Linux. Do you have a patch to
address this in Linux?

--
Stefan


 arch/arm/include/asm/arch-meson/sd_emmc.h | 1 +
 drivers/mmc/meson_gx_mmc.c                | 9 +++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm/include/asm/arch-meson/sd_emmc.h b/arch/arm/include/asm/arch-meson/sd_emmc.h
index cb16f75fc6..db5e058098 100644
--- a/arch/arm/include/asm/arch-meson/sd_emmc.h
+++ b/arch/arm/include/asm/arch-meson/sd_emmc.h
@@ -14,6 +14,7 @@
 
 enum meson_gx_mmc_compatible {
 	MMC_COMPATIBLE_GX,
+	MMC_COMPATIBLE_AGX,
 	MMC_COMPATIBLE_SM1,
 };
 
diff --git a/drivers/mmc/meson_gx_mmc.c b/drivers/mmc/meson_gx_mmc.c
index 5facbfdd9a..2c27113c10 100644
--- a/drivers/mmc/meson_gx_mmc.c
+++ b/drivers/mmc/meson_gx_mmc.c
@@ -64,14 +64,15 @@ static void meson_mmc_config_clock(struct mmc *mmc)
 
 	/*
 	 * SM1 SoCs doesn't work fine over 50MHz with CLK_CO_PHASE_180
+	 * AGX SoCs don't work reliable with some eMMCs with CLK_CO_PHASE_180
 	 * If CLK_CO_PHASE_270 is used, it's more stable than other.
 	 * Other SoCs use CLK_CO_PHASE_180 by default.
 	 * It needs to find what is a proper value about each SoCs.
 	 */
-	if (meson_gx_mmc_is_compatible(mmc->dev, MMC_COMPATIBLE_SM1))
-		meson_mmc_clk |= CLK_CO_PHASE_270;
-	else
+	if (meson_gx_mmc_is_compatible(mmc->dev, MMC_COMPATIBLE_GX))
 		meson_mmc_clk |= CLK_CO_PHASE_180;
+	else
+		meson_mmc_clk |= CLK_CO_PHASE_270;
 
 	/* 180 phase tx clock */
 	meson_mmc_clk |= CLK_TX_PHASE_000;
@@ -327,7 +328,7 @@ int meson_mmc_bind(struct udevice *dev)
 
 static const struct udevice_id meson_mmc_match[] = {
 	{ .compatible = "amlogic,meson-gx-mmc", .data = MMC_COMPATIBLE_GX },
-	{ .compatible = "amlogic,meson-axg-mmc", .data = MMC_COMPATIBLE_GX },
+	{ .compatible = "amlogic,meson-axg-mmc", .data = MMC_COMPATIBLE_AGX },
 	{ .compatible = "amlogic,meson-sm1-mmc", .data = MMC_COMPATIBLE_SM1 },
 	{ /* sentinel */ }
 };
-- 
2.29.2