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From:   Victor Shih <victorshihgli@gmail.com>
Date:   Fri, 17 Nov 2023 18:49:37 +0800
Message-ID: <CAK00qKB6KjNc0vFFTSX4Sx5FcA3OWeMNyLTRCLCdSNt4gRmgbg@mail.gmail.com>
Subject: Re: [PATCH V12 10/23] mmc: sdhci-uhs2: add reset function and
 uhs2_mode function
To:     Ulf Hansson <ulf.hansson@linaro.org>
Cc:     Adrian Hunter <adrian.hunter@intel.com>, linux-mmc@vger.kernel.org,
        linux-kernel@vger.kernel.org, benchuanggli@gmail.com,
        HL.Liu@genesyslogic.com.tw, Greg.tu@genesyslogic.com.tw,
        takahiro.akashi@linaro.org, dlunev@chromium.org,
        Ben Chuang <ben.chuang@genesyslogic.com.tw>,
        Victor Shih <victor.shih@genesyslogic.com.tw>
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On Tue, Oct 10, 2023 at 7:08=E2=80=AFPM Ulf Hansson <ulf.hansson@linaro.org=
> wrote:
>
> On Tue, 10 Oct 2023 at 12:29, Adrian Hunter <adrian.hunter@intel.com> wro=
te:
> >
> > On 4/10/23 11:35, Ulf Hansson wrote:
> > > On Tue, 3 Oct 2023 at 17:03, Adrian Hunter <adrian.hunter@intel.com> =
wrote:
> > >>
> > >> On 3/10/23 15:22, Ulf Hansson wrote:
> > >>> On Tue, 3 Oct 2023 at 13:37, Adrian Hunter <adrian.hunter@intel.com=
> wrote:
> > >>>>
> > >>>> On 3/10/23 13:30, Ulf Hansson wrote:
> > >>>>> On Fri, 15 Sept 2023 at 11:44, Victor Shih <victorshihgli@gmail.c=
om> wrote:
> > >>>>>>
> > >>>>>> From: Victor Shih <victor.shih@genesyslogic.com.tw>
> > >>>>>>
> > >>>>>> Sdhci_uhs2_reset() does a UHS-II specific reset operation.
> > >>>>>>
> > >>>>>> Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
> > >>>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > >>>>>> Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
> > >>>>>> Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> > >>>>>> ---
> > >>>>>>
> > >>>>>> Updates in V8:
> > >>>>>>  - Adjust the position of matching brackets.
> > >>>>>>
> > >>>>>> Updates in V6:
> > >>>>>>  - Remove unnecessary functions and simplify code.
> > >>>>>>
> > >>>>>> ---
> > >>>>>>
> > >>>>>>  drivers/mmc/host/sdhci-uhs2.c | 45 ++++++++++++++++++++++++++++=
+++++++
> > >>>>>>  drivers/mmc/host/sdhci-uhs2.h |  2 ++
> > >>>>>>  2 files changed, 47 insertions(+)
> > >>>>>>
> > >>>>>> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sd=
hci-uhs2.c
> > >>>>>> index e339821d3504..dfc80a7f1bad 100644
> > >>>>>> --- a/drivers/mmc/host/sdhci-uhs2.c
> > >>>>>> +++ b/drivers/mmc/host/sdhci-uhs2.c
> > >>>>>> @@ -10,7 +10,9 @@
> > >>>>>>   *  Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > >>>>>>   */
> > >>>>>>
> > >>>>>> +#include <linux/delay.h>
> > >>>>>>  #include <linux/module.h>
> > >>>>>> +#include <linux/iopoll.h>
> > >>>>>>
> > >>>>>>  #include "sdhci.h"
> > >>>>>>  #include "sdhci-uhs2.h"
> > >>>>>> @@ -49,6 +51,49 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *=
host)
> > >>>>>>  }
> > >>>>>>  EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
> > >>>>>>
> > >>>>>> +/**************************************************************=
***************\
> > >>>>>> + *                                                             =
              *
> > >>>>>> + * Low level functions                                         =
              *
> > >>>>>> + *                                                             =
              *
> > >>>>>> +\**************************************************************=
***************/
> > >>>>>> +
> > >>>>>> +bool sdhci_uhs2_mode(struct sdhci_host *host)
> > >>>>>> +{
> > >>>>>> +       return host->mmc->flags & MMC_UHS2_SUPPORT;
> > >>>>>
> > >>>>> The MMC_UHS2_SUPPORT bit looks redundant to me. Instead, I think =
we
> > >>>>> should be using mmc->ios.timings, which already indicates whether=
 we
> > >>>>> are using UHS2 (MMC_TIMING_UHS2_SPEED_*). See patch2 where we add=
ed
> > >>>>> this.
> > >>>>>
> > >>>>> That said, I think we should drop the sdhci_uhs2_mode() function
> > >>>>> altogether and instead use mmc_card_uhs2(), which means we should=
 move
> > >>>>> it to include/linux/mmc/host.h, so it becomes available for host
> > >>>>> drivers.
> > >>>>>
> > >>>>
> > >>>> UHS2 mode starts at UHS2 initialization and ends either when UHS2
> > >>>> initialization fails, or the card is removed.
> > >>>>
> > >>>> So it includes re-initialization and reset when the transfer mode
> > >>>> currently transitions through MMC_TIMING_LEGACY.
> > >>>>
> > >>>> So mmc_card_uhs2() won't work correctly for the host callbacks
> > >>>> unless something is done about that.
> > >>>
> > >>> Right, thanks for clarifying!
> > >>>
> > >>> In that case I wonder if we couldn't change the way we update the
> > >>> ->ios.timing for UHS2. It seems silly to have two (similar) ways to
> > >>> indicate that we have moved to UHS2.
> > >>
> > >> Perhaps something like below:
> > >>
> > >> diff --git a/drivers/mmc/core/sd_uhs2.c b/drivers/mmc/core/sd_uhs2.c
> > >> index aacefdd6bc9e..e39d63d46041 100644
> > >> --- a/drivers/mmc/core/sd_uhs2.c
> > >> +++ b/drivers/mmc/core/sd_uhs2.c
> > >> @@ -70,7 +70,8 @@ static int sd_uhs2_power_off(struct mmc_host *host=
)
> > >>
> > >>         host->ios.vdd =3D 0;
> > >>         host->ios.clock =3D 0;
> > >> -       host->ios.timing =3D MMC_TIMING_LEGACY;
> > >> +       /* Must set UHS2 timing to identify UHS2 mode */
> > >> +       host->ios.timing =3D MMC_TIMING_UHS2_SPEED_A;
> > >>         host->ios.power_mode =3D MMC_POWER_OFF;
> > >>         if (host->flags & MMC_UHS2_SD_TRAN)
> > >>                 host->flags &=3D ~MMC_UHS2_SD_TRAN;
> > >> @@ -1095,7 +1096,8 @@ static void sd_uhs2_detect(struct mmc_host *ho=
st)
> > >>                 mmc_claim_host(host);
> > >>                 mmc_detach_bus(host);
> > >>                 sd_uhs2_power_off(host);
> > >> -               host->flags &=3D ~MMC_UHS2_SUPPORT;
> > >> +               /* Remove UHS2 timing to indicate the end of UHS2 mo=
de */
> > >> +               host->ios.timing =3D MMC_TIMING_LEGACY;
> > >>                 mmc_release_host(host);
> > >>         }
> > >>  }
> > >> @@ -1338,7 +1340,8 @@ static int sd_uhs2_attach(struct mmc_host *hos=
t)
> > >>  err:
> > >>         mmc_detach_bus(host);
> > >>         sd_uhs2_power_off(host);
> > >> -       host->flags &=3D ~MMC_UHS2_SUPPORT;
> > >> +       /* Remove UHS2 timing to indicate the end of UHS2 mode */
> > >> +       host->ios.timing =3D MMC_TIMING_LEGACY;
> > >>         return err;
> > >>  }
> > >
> > > I wouldn't mind changing to the above. But, maybe an even better
> > > option is to use the ->timing variable in the struct sdhci_host, as
> > > it's there already to keep track of the current/previous timing state=
.
> > > Would that work too?
> >
> > The host does not really have enough information.
>
> Okay, let's go with the approach you suggested above/below then!
>

Hi, Ulf and Adrian

I will update this in version 13.

Thanks, Victor Shih

> >
> > >
> > >>
> > >> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-=
uhs2.c
> > >> index 517c497112f4..d1f3318b7d3a 100644
> > >> --- a/drivers/mmc/host/sdhci-uhs2.c
> > >> +++ b/drivers/mmc/host/sdhci-uhs2.c
> > >> @@ -267,10 +267,11 @@ static void __sdhci_uhs2_set_ios(struct mmc_ho=
st *mmc, struct mmc_ios *ios)
> > >>
> > >>         /* UHS2 timing. Note, UHS2 timing is disabled when powering =
off */
> > >>         ctrl_2 =3D sdhci_readw(host, SDHCI_HOST_CONTROL2);
> > >> -       if (ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_A ||
> > >> -           ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_A_HD ||
> > >> -           ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_B ||
> > >> -           ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_B_HD)
> > >> +       if (ios->power_mode !=3D MMC_POWER_OFF &&
> > >> +           (ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_A ||
> > >> +            ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_A_HD ||
> > >> +            ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_B ||
> > >> +            ios->timing =3D=3D MMC_TIMING_UHS2_SPEED_B_HD))
> > >>                 ctrl_2 |=3D SDHCI_CTRL_UHS2 | SDHCI_CTRL_UHS2_ENABLE=
;
> > >>         else
> > >>                 ctrl_2 &=3D ~(SDHCI_CTRL_UHS2 | SDHCI_CTRL_UHS2_ENAB=
LE);
> > >>
> > >>
>
> Kind regards
> Uffe