Re: [PATCH v3 1/3] arm: dts: rk3288-tinker.dtsi: Fix SD card detection

[Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>]

On 2019-03-12 2:08 pm, Heiko Stuebner wrote:
> Am Samstag, 9. März 2019, 16:39:21 CET schrieb David Summers:
>> 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@davidjohnsummers.uk>
>> Reviewed by: Robin Murphy <robin.murphy@arm.com>
>> Reviewed by: Jonas Karlman <jonas@kwiboo.se>
>> Test by: TheSaint @ ArchLinux Arm
> 
> please follow patch submission guidelines, here it would be
> Tested-by: ... with an actual Name + mail address
> 
> Also I did try to go through the way big mail thread but didn't
> find an actual "Reviewed-by" from Robin Murphy, similar to what
> he pointed out in patch2

Ah, I didn't get a direct CC of this patch so I hadn't spotted that - 
FWIW though, I'm happy with Doug's reasoning for "broken-cd" being the 
most robust solution for now, so feel free to keep

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

for this one.

Cheers,
Robin.

> 
> Other than that and including the past discussions, this looks good.
> 
> 
> Heiko
> 
>> ---
>>   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>;
>>
> 
> 
> 
> 

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