From 97237b5b6bee9d1915792dd9911f630a8f44076e Mon Sep 17 00:00:00 2001 From: Jakob Unterwurzacher Date: Tue, 17 Jul 2018 16:24:43 +0200 Subject: rk3399-puma.dts: reduce sd card max-frequency to 40MHz. 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. Signed-off-by: Jakob Unterwurzacher --- arch/arm64/boot/dts/rockchip/rk3399-puma.dts | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dts b/arch/arm64/boot/dts/rockchip/rk3399-puma.dts index 58f91de211cd..d2304dd611de 100644 --- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dts +++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dts @@ -695,7 +695,7 @@ &sdmmc { // On the AP6255 Wifi module, firmware download fails above 25 MHz. Set to 10 MHz to be safe. //max-frequency = <10000000>; - max-frequency = <50000000>; // 50 MHz = High Speed 3.3V + max-frequency = <40000000>; supports-sdio; supports-sd; bus-width = <4>; -- cgit v1.2.3