The Problem: On ASUS Tinker Board S, when booting from the eMMC, and there is card in the sd slot, there are constant errors. Also when warm reboot, uboot can not access the sd slot Cause: Identified by Robin Murphy @ ARM. The Card Detect on rk3288 devices is pulled up by vccio-sd; so when the regulator powers this off, card detect gives spurious errors. A second problem, is during power down, vccio-sd apprears to be powered down. This causes a problem when warm rebooting from the sd card. This was identified by Jonas Karlman. History: A common fault on these rk3288 board, which impliment the reference design. When this arose before: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-August/281153.html And Ulf and Jaehoon clearly said this was a broken card detect design, which should be solved via polling Solution: Hence broken-cd is set as a property. This cures the errors. The powering down of vccio-sd during reboot is cured by adding regulator-boot-on. This solutions has been fairly widely reviewed and tested. Signed-off-by: David Summers <beagleboard@xxxxxxxxxxxxxxxxxxx> Reviewed by: Robin Murphy <robin.murphy@xxxxxxx> Reviewed by: Jonas Karlman <jonas@xxxxxxxxx> Test by: TheSaint @ ArchLinux Arm --- arch/arm/boot/dts/rk3288-tinker.dtsi | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/rk3288-tinker.dtsi b/arch/arm/boot/dts/rk3288-tinker.dtsi index aa107ee41b8b..ef653c3209bc 100644 --- a/arch/arm/boot/dts/rk3288-tinker.dtsi +++ b/arch/arm/boot/dts/rk3288-tinker.dtsi @@ -254,6 +254,7 @@ }; vccio_sd: LDO_REG5 { + regulator-boot-on; regulator-min-microvolt = <1800000>; regulator-max-microvolt = <3300000>; regulator-name = "vccio_sd"; @@ -430,7 +431,7 @@ bus-width = <4>; cap-mmc-highspeed; cap-sd-highspeed; - card-detect-delay = <200>; + broken-cd; disable-wp; /* wp not hooked up */ pinctrl-names = "default"; pinctrl-0 = <&sdmmc_clk &sdmmc_cmd &sdmmc_cd &sdmmc_bus4>; -- beagleboard@xxxxxxxxxxxxxxxxxxx
