[PATCH 2/2] mmc: fsl_esdhc_imx: add extra delay for IO voltage switch if necessary

[Sean Anderson]

On 3/22/21 8:04 AM, Fabio Estevam wrote:
> Hi Haibo,
> 
> On Mon, Mar 22, 2021 at 8:09 AM <haibo.chen at nxp.com> wrote:
> 
>> --- a/arch/arm/dts/imx8mm-evk-u-boot.dtsi
>> +++ b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
>> @@ -102,6 +102,7 @@
>>          u-boot,dm-spl;
>>          sd-uhs-sdr104;
>>          sd-uhs-ddr50;
>> +       fsl,signal-voltage-switch-extra-delay-ms = <8>;
> 
> How does the Linux kernel deal with that?
> 
> I don't see such property in the mainline kernel or in the NXP tree.
> 
> I am concerned that we add a U-Boot specific here. Also, the fact that
> common code waits 10ms is a driver implementation detail, so not happy
> that such information needs to be passed in the U-Boot dts.
> 

Typically they wait in the regulator. E.g. regulator-ramp-delay or
regulator-settling-time-us. There should be no need to wait in the MMC
driver.

--Sean