Re: [PATCH v2] mmc: mmci: manage MMC_PM_KEEP_POWER per variant config

[Yann Gautier]

On 3/14/22 14:03, Ulf Hansson wrote:
> On Mon, 14 Mar 2022 at 13:56, Yann Gautier <yann.gautier@xxxxxxxxxxx> wrote:
> > Add a disable_keep_power field in variant_data struct. The
> > MMC_PM_KEEP_POWER flag will be enabled if disable_keep_power is not set.
> > It is only set to true for stm32_sdmmc variants.
> >
> > The issue was seen on STM32MP157C-DK2 board, which embeds a wifi chip.
> > It doesn't correctly support low power on this board. The Wifi chip
> > awaits an always-on regulator, but it was connected to v3v3 which is off
> > in low-power sequence. MMC_PM_KEEP_POWER should then be disabled.
>
> Just to make sure I get this correct.
>
> Why can't the regulator stay on during system suspend? The point is,
> we don't need an always on regulator to cope with this.
>
> Kind regards
> Uffe

Hi Ulf,

This v3v3 regulator powers most of the devices on this board. So we need 
to switch it off to gain power in suspend mode.


Yann

> > The flag can still be enabled through DT property:
> > keep-power-in-suspend.
> >
> > Signed-off-by: Yann Gautier <yann.gautier@xxxxxxxxxxx>
> > ---
> > Update in v2:
> > Reword commit message to better explain the issue.
> >
> > Resend the patch alone. It was previoulsy in a series [1] for which the
> > other patches will be reworked.
> >
> > [1] https://lore.kernel.org/lkml/20220304135134.47827-1-yann.gautier@xxxxxxxxxxx/
> >
> >   drivers/mmc/host/mmci.c | 5 ++++-
> >   drivers/mmc/host/mmci.h | 1 +
> >   2 files changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> > index 45b8608c935c..0e2f2f5d6a52 100644
> > --- a/drivers/mmc/host/mmci.c
> > +++ b/drivers/mmc/host/mmci.c
> > @@ -274,6 +274,7 @@ static struct variant_data variant_stm32_sdmmc = {
> >          .busy_detect            = true,
> >          .busy_detect_flag       = MCI_STM32_BUSYD0,
> >          .busy_detect_mask       = MCI_STM32_BUSYD0ENDMASK,
> > +       .disable_keep_power     = true,
> >          .init                   = sdmmc_variant_init,
> >   };
> >
> > @@ -301,6 +302,7 @@ static struct variant_data variant_stm32_sdmmcv2 = {
> >          .busy_detect            = true,
> >          .busy_detect_flag       = MCI_STM32_BUSYD0,
> >          .busy_detect_mask       = MCI_STM32_BUSYD0ENDMASK,
> > +       .disable_keep_power     = true,
> >          .init                   = sdmmc_variant_init,
> >   };
> >
> > @@ -2172,7 +2174,8 @@ static int mmci_probe(struct amba_device *dev,
> >          host->stop_abort.flags = MMC_RSP_R1B | MMC_CMD_AC;
> >
> >          /* We support these PM capabilities. */
> > -       mmc->pm_caps |= MMC_PM_KEEP_POWER;
> > +       if (!variant->disable_keep_power)
> > +               mmc->pm_caps |= MMC_PM_KEEP_POWER;
> >
> >          /*
> >           * We can do SGIO
> > diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> > index e1a9b96a3396..2cad1ef9766a 100644
> > --- a/drivers/mmc/host/mmci.h
> > +++ b/drivers/mmc/host/mmci.h
> > @@ -361,6 +361,7 @@ struct variant_data {
> >          u32                     opendrain;
> >          u8                      dma_lli:1;
> >          u32                     stm32_idmabsize_mask;
> > +       u8                      disable_keep_power:1;
> >          void (*init)(struct mmci_host *host);
> >   };
> >
> > --
> > 2.25.1