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(-)
Applied to u-boot-rockchip, thanks!