[Linux-stm32] [PATCH] ARM: dts: stm32: Consistently enable internal pull-ups for SD bus

[Marek Vasut]

On 10/14/20 4:52 PM, Yann GAUTIER wrote:
> 
> 
> On 10/14/20 3:30 PM, Marek Vasut wrote:
>> On 10/14/20 3:26 PM, Yann GAUTIER wrote:
>> [...]
>>>> diff --git a/arch/arm/boot/dts/stm32mp15-pinctrl.dtsi b/arch/arm/boot/dts/stm32mp15-pinctrl.dtsi
>>>> index b2d19583450c..73d9a5b7f5ba 100644
>>>> --- a/arch/arm/boot/dts/stm32mp15-pinctrl.dtsi
>>>> +++ b/arch/arm/boot/dts/stm32mp15-pinctrl.dtsi
>>>> @@ -1291,13 +1291,13 @@ pins1 {
>>>>    				 <STM32_PINMUX('D', 2, AF12)>; /* SDMMC1_CMD */
>>>>    			slew-rate = <1>;
>>>>    			drive-push-pull;
>>>> -			bias-disable;
>>>> +			bias-pull-up;
>>> Hi Marek,
>>
>> Hi,
>>
>>> This pin config is used by ST board, where we have a level shifter.
>>> This shouldn't be changed. We discussed this with Alex, and a new group
>>> should be added in this case.
>>
>> Is it a problem if we enable the pulls up unconditionally with the level
>> shifter present, to make the properties of the SD bus consistent ?
>>
> The risk of having 2 parallel pull-ups is that the resulting value could 
> be below the lower acceptable value for SD. I'll check if that can occur.

That's a good idea, thank you!