Re: [RFC] mmc: meson-gx-mmc: add delay during poweroff

[Da Xue]

On Wed, Jul 2, 2025 at 2:40 PM Martin Blumenstingl
<martin.blumenstingl@xxxxxxxxxxxxxx> wrote:
>
> On Wed, Jul 2, 2025 at 7:22 PM Da Xue <da@libre.computer> wrote:
> >
> > On Wed, Jul 2, 2025 at 1:07 PM Jerome Brunet <jbrunet@xxxxxxxxxxxx> wrote:
> > ...
> > > If, as the description suggest, the regulator framework somehow ignore
> > > the timing set in DT, maybe this is what needs to be checked ?
> >
> > The regulator framework only cares about timing for regulator on.
> > Regulator off just turns off the regulator and returns without delay.
> There's an exception to this: gpio-regulators without an enable-gpios
> property. My understanding is that regulator_disable() is a no-op in
> that case (meson_mmc_set_ios() even has a comment above the
> switch/case statement), see [0].
>
> > The code makes incorrect assumptions. Then the kernel resets the board
> > without having enough time.
> Can you please name the board you're testing? I'm worried that I'll be
> looking at one .dts but you're looking at another one.

https://github.com/libre-computer-project/libretech-linux/blob/master/arch/arm64/boot/dts/amlogic/meson-libretech-cottonwood.dtsi#L481

vcc_card is a gpio regulator that gets toggled on->off->on.

I traced the regulator framework a few weeks ago and forgot the final
regulator disable function call, but that call basically returned
immediately while the regulator-enable function complement had delays
implemented.

>
>
> Best regards,
> Martin
>
>
> [0] https://elixir.bootlin.com/linux/v6.15/source/drivers/regulator/core.c#L2980