Some SanDisk Ultra cards trigger intermittent errors on detection resulting in an -EOPNOTSUPP, when running at 50MHz.

Waveform analysis suggest that the level shifters that are used on the RK3399-Q7 module (for voltage translation between the on-module voltages and the 3.3V required on the card-edge) don't handle clock rates at or above 48MHz properly. This change reduces the maximum frequency on the external SD-interface to 40MHz (for a safety margin of 20%).

Reported-by: Jakob Unterwurzacher jakob.unterwurzacher@theobroma-systems.com Signed-off-by: Philipp Tomsich philipp.tomsich@theobroma-systems.com Tested-by: Christoph Muellner christoph.muellner@theobroma-systems.com ---

arch/arm/dts/rk3399-puma.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/dts/rk3399-puma.dtsi b/arch/arm/dts/rk3399-puma.dtsi index 261df42..ba9bb4c 100644 --- a/arch/arm/dts/rk3399-puma.dtsi +++ b/arch/arm/dts/rk3399-puma.dtsi @@ -505,7 +505,7 @@ &sdmmc { u-boot,dm-pre-reloc; clock-frequency = <150000000>; - clock-freq-min-max = <100000 150000000>; + max-frequency = <40000000>; supports-sd; bus-width = <4>; cap-mmc-highspeed;