Hi David, On 2019-02-17 12:15 pm, David Summers wrote:
This patch makes some minor changes to how the sd card is described in the device tree for the ASUS Tinker Board (S). In particular on the Tinker Board S, when booted from the eMMC, and with no card in the sd slot, and the log has endless messages about not being able to detect the card. Several methods to remove this error have been tried, the only one that works is the broken-cd and so that is what is applied here.
I don't have a Tinker Board, but the symptom sounds instantly familiar from hacking on another RK3288 box; have you tried adding "regulator-always-on" to the vccio_sd regulator?
With the reference design (which I would assume the Tinker Board has no reason to deviate from in this area), the CD pin is either wired directly to the SoC with no external pull-up, or explicitly pulled up to VCCIO_SD. Either way, when the dwmmc driver probes and discovers there is no card present, it sets the currently-unnecessary vqmmc-supply as inactive, and thus the regulator core turns off VCCIO_SD entirely. Unfortunately, this removes the voltage from the entire I/O domain including the internal pull-up, which ends up leaving the CD pin floating and generating spurious events.
Robin.
Alas the ASUS schematic is not clear enough to indicate if the card detect is wired up to the cpu, the schematic does not show internal wiring on the Tinker Board! Now this error didn't show up on the Tinker Board, as that machine only boots where there is a sd card installed. However as the TB and TBS are so similar it is expected that the Tinker Board also doesn't have a functioning card detect. Hence the change here is made to the dtsi file, so it applies to both TB and TBS. The disable-wp is also removed, it doesnt seem needed on the micro sdcard slots, and without thisn the card can still be written to. Hence this flag is also removed. Signed-off-by: David Summers <beagleboard@xxxxxxxxxxxxxxxxxxx> --- arch/arm/boot/dts/rk3288-tinker.dtsi | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/arm/boot/dts/rk3288-tinker.dtsi b/arch/arm/boot/dts/rk3288-tinker.dtsi index 2b38075a2917..fceaeed44e34 100644 --- a/arch/arm/boot/dts/rk3288-tinker.dtsi +++ b/arch/arm/boot/dts/rk3288-tinker.dtsi @@ -432,9 +432,7 @@ bus-width = <4>; cap-mmc-highspeed; cap-sd-highspeed; - card-detect-delay = <200>; - disable-wp; /* wp not hooked up */ + broken-cd; pinctrl-names = "default"; pinctrl-0 = <&sdmmc_clk &sdmmc_cmd &sdmmc_cd &sdmmc_bus4>; status = "okay";
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