linux-kernel - Re: [PATCH v2] mmc: host: Wait for Vdd to settle on card power off

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Message-ID: <CAPDyKFrOWHGVNHtKpaY02AXV9AV0NT6LoK2grcN9FTQmVOj7kA@mail.gmail.com>
Date: Thu, 20 Mar 2025 15:16:43 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Adrian Hunter <adrian.hunter@...el.com>, Erick Shepherd <erick.shepherd@...com>
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mmc: host: Wait for Vdd to settle on card power off

On Thu, 20 Mar 2025 at 08:26, Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 14/03/25 21:50, Erick Shepherd wrote:
> > The SD spec version 6.0 section 6.4.1.5 requires that Vdd must be
> > lowered to less than 0.5V for a minimum of 1 ms when powering off a
> > card. Increase wait to 15 ms so that voltage has time to drain down
> > to 0.5V and cards can power off correctly. Issues with voltage drain
> > time were only observed on Apollo Lake and Bay Trail host controllers
> > so this fix is limited to those devices.
> >
> > Signed-off-by: Erick Shepherd <erick.shepherd@...com>
>
> Can we leave a blank line after the block.  It was that way before.
>
> With that, you can add:
>
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>

Applied for next with the suggested change, thanks!

Kind regards
Uffe


>
> > ---
> >  drivers/mmc/host/sdhci-pci-core.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> > index 1f0bd723f011..b1f7c11ea61e 100644
> > --- a/drivers/mmc/host/sdhci-pci-core.c
> > +++ b/drivers/mmc/host/sdhci-pci-core.c
> > @@ -610,9 +610,12 @@ static void sdhci_intel_set_power(struct sdhci_host *host, unsigned char mode,
> >
> >       sdhci_set_power(host, mode, vdd);
> >
> > -     if (mode == MMC_POWER_OFF)
> > +     if (mode == MMC_POWER_OFF) {
> > +             if (slot->chip->pdev->device == PCI_DEVICE_ID_INTEL_APL_SD ||
> > +                 slot->chip->pdev->device == PCI_DEVICE_ID_INTEL_BYT_SD)
> > +                     usleep_range(15000, 17500);
> >               return;
> > -
> > +     }
>
> Blank line here
>
> >       /*
> >        * Bus power might not enable after D3 -> D0 transition due to the
> >        * present state not yet having propagated. Retry for up to 2ms.
>