linux-kernel - Re: [PATCH] mmc: sdhci: Fix warning message when accessing RPMB in HS400 mode

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Message-ID: <CAPDyKFqzcFkU-tWEMyFLVxBekXuWUMpV-gHCt=1wf-rY=Nz5gQ@mail.gmail.com>
Date:   Fri, 2 Jul 2021 15:22:11 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Alan Cooper <alcooperx@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-mmc <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH] mmc: sdhci: Fix warning message when accessing RPMB in
 HS400 mode

On Fri, 2 Jul 2021 at 14:34, Alan Cooper <alcooperx@...il.com> wrote:
>
> On Wed, Jun 30, 2021 at 10:21 AM Ulf Hansson <ulf.hansson@...aro.org> wrote:
> >
> > On Thu, 24 Jun 2021 at 18:31, Al Cooper <alcooperx@...il.com> wrote:
> > >
> > > When an eMMC device is being run in HS400 mode, any access to the
> > > RPMB device will cause the error message "mmc1: Invalid UHS-I mode
> > > selected". This happens as a result of tuning being disabled before
> > > RPMB access and then re-enabled after the RPMB access is complete.
> > > When tuning is re-enabled, the system has to switch from HS400
> > > to HS200 to do the tuning and then back to HS400. As part of
> > > sequence to switch from HS400 to HS200 the system is temporarily
> > > put into HS mode. When switching to HS mode, sdhci_get_preset_value()
> > > is called and does not have support for HS mode and prints the warning
> > > message and returns the preset for SDR12. The fix is to add support
> > > for MMC and SD HS modes to sdhci_get_preset_value().
> > >
> > > This can be reproduced on any system running eMMC in HS400 mode
> > > (not HS400ES) by using the "mmc" utility to run the following
> > > command: "mmc rpmb read-counter /dev/mmcblk0rpmb".
> > >
> > > Signed-off-by: Al Cooper <alcooperx@...il.com>
> >
> > I assume we want this for stable kernels, but it would be nice to add
> > a fixes tag as well.
> >
> > Do you know if there is a specific commit that this fixes?
>
> The function sdhci_get_preset_value(), which is missing the HS modes,
> was added in 52983382c74f5 for v3.9. Should I add a fixes tag for that
> commit?

Thanks for checking this! I have amended the patch to add a
fixes/stable tag and applied it for fixes.

Kind regards
Uffe

>
> Thanks
> Al
>
> >
> > Kind regards
> > Uffe
> >
> > > ---
> > >  drivers/mmc/host/sdhci.c | 4 ++++
> > >  drivers/mmc/host/sdhci.h | 1 +
> > >  2 files changed, 5 insertions(+)
> > >
> > > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > > index bf238ade1602..6b39126fbf06 100644
> > > --- a/drivers/mmc/host/sdhci.c
> > > +++ b/drivers/mmc/host/sdhci.c
> > > @@ -1812,6 +1812,10 @@ static u16 sdhci_get_preset_value(struct sdhci_host *host)
> > >         u16 preset = 0;
> > >
> > >         switch (host->timing) {
> > > +       case MMC_TIMING_MMC_HS:
> > > +       case MMC_TIMING_SD_HS:
> > > +               preset = sdhci_readw(host, SDHCI_PRESET_FOR_HIGH_SPEED);
> > > +               break;
> > >         case MMC_TIMING_UHS_SDR12:
> > >                 preset = sdhci_readw(host, SDHCI_PRESET_FOR_SDR12);
> > >                 break;
> > > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > > index 0770c036e2ff..960fed78529e 100644
> > > --- a/drivers/mmc/host/sdhci.h
> > > +++ b/drivers/mmc/host/sdhci.h
> > > @@ -253,6 +253,7 @@
> > >
> > >  /* 60-FB reserved */
> > >
> > > +#define SDHCI_PRESET_FOR_HIGH_SPEED    0x64
> > >  #define SDHCI_PRESET_FOR_SDR12 0x66
> > >  #define SDHCI_PRESET_FOR_SDR25 0x68
> > >  #define SDHCI_PRESET_FOR_SDR50 0x6A
> > >
> > > base-commit: 7426cedc7dad67bf3c71ea6cc29ab7822e1a453f
> > > --
> > > 2.17.1
> > >