[PATCH] arm64: dts: rockchip: lower rk3399-puma-haikou SD controller clock frequency

[Quentin Schulz]

From: Quentin Schulz <quentin.schulz at theobroma-systems.com>

From: Jakob Unterwurzacher <jakob.unterwurzacher at theobroma-systems.com>

CRC errors (code -84 EILSEQ) have been observed for some SanDisk
Ultra A1 cards when running at 50MHz.

Waveform analysis suggest that the level shifters that are used on the
RK3399-Q7 module for voltage translation between 3.0 and 3.3V don't
handle clock rates at or above 48MHz properly. Back off to 40MHz for
some safety margin.

Cc: stable at vger.kernel.org
Fixes: 60fd9f72ce8a ("arm64: dts: rockchip: add Haikou baseboard with RK3399-Q7 SoM")
Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher at theobroma-systems.com>
Signed-off-by: Quentin Schulz <quentin.schulz at theobroma-systems.com>
---
We've been carrying this patch downstream for years and completely forgot to
upstream it. This is now done.

To: Rob Herring <robh+dt at kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt at linaro.org>
To: Heiko Stuebner <heiko at sntech.de>
Cc: devicetree at vger.kernel.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-rockchip at lists.infradead.org
Cc: linux-kernel at vger.kernel.org
Cc: Jakob Unterwurzacher <jakob.unterwurzacher at theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-puma-haikou.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma-haikou.dts b/arch/arm64/boot/dts/rockchip/rk3399-puma-haikou.dts
index 04c752f49be9..115c14c0a3c6 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma-haikou.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma-haikou.dts
@@ -207,7 +207,7 @@ &sdmmc {
 	cap-sd-highspeed;
 	cd-gpios = <&gpio0 RK_PA7 GPIO_ACTIVE_LOW>;
 	disable-wp;
-	max-frequency = <150000000>;
+	max-frequency = <40000000>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&sdmmc_clk &sdmmc_cmd &sdmmc_cd &sdmmc_bus4>;
 	vmmc-supply = <&vcc3v3_baseboard>;

---
base-commit: aae703b02f92bde9264366c545e87cec451de471
change-id: 20221019-upstream-puma-sd-40mhz-b5aef1c351e6

Best regards,
-- 
Quentin Schulz <quentin.schulz at theobroma-systems.com>