Message-ID: <CAD=FV=UA9i1eEi3Mx0WF-DnCnr4O4-MfOxa=axZOJtXzxbV7Tw@mail.gmail.com>
Date:   Fri, 14 Jun 2019 09:41:24 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Arend van Spriel <arend.vanspriel@...adcom.com>,
        brcm80211-dev-list.pdl@...adcom.com,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Double Lo <double.lo@...ress.com>,
        Brian Norris <briannorris@...omium.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Naveen Gupta <naveen.gupta@...ress.com>,
        Madhan Mohan R <madhanmohan.r@...ress.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        Wright Feng <wright.feng@...ress.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        netdev <netdev@...r.kernel.org>,
        brcm80211-dev-list <brcm80211-dev-list@...ress.com>,
        Jiong Wu <lohengrin1024@...il.com>,
        Ritesh Harjani <riteshh@...eaurora.org>,
        Allison Randal <allison@...utok.net>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Avri Altman <avri.altman@....com>
Subject: Re: [PATCH v4 2/5] mmc: core: API to temporarily disable retuning for
 SDIO CRC errors

Hi,

On Fri, Jun 14, 2019 at 5:04 AM Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
> On Fri, 14 Jun 2019 at 01:42, Douglas Anderson <dianders@...omium.org> wrote:
> >
> > Normally when the MMC core sees an "-EILSEQ" error returned by a host
> > controller then it will trigger a retuning of the card.  This is
> > generally a good idea.
> >
> > However, if a command is expected to sometimes cause transfer errors
> > then these transfer errors shouldn't cause a re-tuning.  This
> > re-tuning will be a needless waste of time.  One example case where a
> > transfer is expected to cause errors is when transitioning between
> > idle (sometimes referred to as "sleep" in Broadcom code) and active
> > state on certain Broadcom WiFi SDIO cards.  Specifically if the card
> > was already transitioning between states when the command was sent it
> > could cause an error on the SDIO bus.
> >
> > Let's add an API that the SDIO function drivers can call that will
> > temporarily disable the auto-tuning functionality.  Then we can add a
> > call to this in the Broadcom WiFi driver and any other driver that
> > might have similar needs.
> >
> > NOTE: this makes the assumption that the card is already tuned well
> > enough that it's OK to disable the auto-retuning during one of these
> > error-prone situations.  Presumably the driver code performing the
> > error-prone transfer knows how to recover / retry from errors.  ...and
> > after we can get back to a state where transfers are no longer
> > error-prone then we can enable the auto-retuning again.  If we truly
> > find ourselves in a case where the card needs to be retuned sometimes
> > to handle one of these error-prone transfers then we can always try a
> > few transfers first without auto-retuning and then re-try with
> > auto-retuning if the first few fail.
> >
> > Without this change on rk3288-veyron-minnie I periodically see this in
> > the logs of a machine just sitting there idle:
> >   dwmmc_rockchip ff0d0000.dwmmc: Successfully tuned phase to XYZ
> >
> > Fixes: bd11e8bd03ca ("mmc: core: Flag re-tuning is needed on CRC errors")
> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > ---
> >
> > Changes in v4:
> > - Moved to SDIO API only (Adrian, Ulf).
> > - Renamed to make it less generic, now retune_crc_disable (Ulf).
> > - Function header makes it clear host must be claimed (Ulf).
> > - No more WARN_ON (Ulf).
> >
> > Changes in v3:
> > - Took out the spinlock since I believe this is all in one context.
> >
> > Changes in v2:
> > - Updated commit message to clarify based on discussion of v1.
> >
> >  drivers/mmc/core/core.c       |  5 +++--
> >  drivers/mmc/core/sdio_io.c    | 36 +++++++++++++++++++++++++++++++++++
> >  include/linux/mmc/core.h      |  2 ++
> >  include/linux/mmc/host.h      |  1 +
> >  include/linux/mmc/sdio_func.h |  3 +++
> >  5 files changed, 45 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > index 6db36dc870b5..9020cb2490f7 100644
> > --- a/drivers/mmc/core/core.c
> > +++ b/drivers/mmc/core/core.c
> > @@ -144,8 +144,9 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
> >         int err = cmd->error;
> >
> >         /* Flag re-tuning needed on CRC errors */
> > -       if ((cmd->opcode != MMC_SEND_TUNING_BLOCK &&
> > -           cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200) &&
> > +       if (cmd->opcode != MMC_SEND_TUNING_BLOCK &&
> > +           cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200 &&
> > +           !host->retune_crc_disable &&
> >             (err == -EILSEQ || (mrq->sbc && mrq->sbc->error == -EILSEQ) ||
> >             (mrq->data && mrq->data->error == -EILSEQ) ||
> >             (mrq->stop && mrq->stop->error == -EILSEQ)))
> > diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
> > index f79f0b0caab8..f822a9630b0e 100644
> > --- a/drivers/mmc/core/sdio_io.c
> > +++ b/drivers/mmc/core/sdio_io.c
> > @@ -734,3 +734,39 @@ int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags)
> >         return 0;
> >  }
> >  EXPORT_SYMBOL_GPL(sdio_set_host_pm_flags);
> > +
> > +/**
> > + *     sdio_retune_crc_disable - temporarily disable retuning on CRC errors
> > + *     @func: SDIO function attached to host
> > + *
> > + *     If the SDIO card is known to be in a state where it might produce
> > + *     CRC errors on the bus in response to commands (like if we know it is
> > + *     transitioning between power states), an SDIO function driver can
> > + *     call this function to temporarily disable the SD/MMC core behavior of
> > + *     triggering an automatic retuning.
> > + *
> > + *     This function should be called while the host is claimed and the host
> > + *     should remain claimed until sdio_retune_crc_enable() is called.
> > + *     Specifically, the expected sequence of calls is:
> > + *     - sdio_claim_host()
> > + *     - sdio_retune_crc_disable()
> > + *     - some number of calls like sdio_writeb() and sdio_readb()
>
> sdio_retune_crc_enable()
>
> > + *     - sdio_release_host()
> > + */
> > +void sdio_retune_crc_disable(struct sdio_func *func)
> > +{
> > +       func->card->host->retune_crc_disable = true;
> > +}
> > +EXPORT_SYMBOL_GPL(sdio_retune_crc_disable);
> > +
> > +/**
> > + *     sdio_retune_crc_enable - reneable retuning on CRC errors
>
> /s/reneable/re-enable
>
> > + *     @func: SDIO function attached to host
> > + *
> > + *     This is the compement to sdio_retune_crc_disable().
> > + */
> > +void sdio_retune_crc_enable(struct sdio_func *func)
> > +{
> > +       func->card->host->retune_crc_disable = false;
> > +}
> > +EXPORT_SYMBOL_GPL(sdio_retune_crc_enable);
> > diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
> > index 134a6483347a..02a13abf0cda 100644
> > --- a/include/linux/mmc/core.h
> > +++ b/include/linux/mmc/core.h
> > @@ -178,6 +178,8 @@ int mmc_wait_for_cmd(struct mmc_host *host, struct mmc_command *cmd,
> >
> >  int mmc_hw_reset(struct mmc_host *host);
> >  int mmc_sw_reset(struct mmc_host *host);
> > +void mmc_expect_errors_begin(struct mmc_host *host);
> > +void mmc_expect_errors_end(struct mmc_host *host);
>
> Leftovers for earlier versions.

Oops!


> >  void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card);
> >
> >  #endif /* LINUX_MMC_CORE_H */
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index 43d0f0c496f6..ecb7972e2423 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -398,6 +398,7 @@ struct mmc_host {
> >         unsigned int            retune_now:1;   /* do re-tuning at next req */
> >         unsigned int            retune_paused:1; /* re-tuning is temporarily disabled */
> >         unsigned int            use_blk_mq:1;   /* use blk-mq */
> > +       unsigned int            retune_crc_disable:1; /* don't trigger retune upon crc */
> >
> >         int                     rescan_disable; /* disable card detection */
> >         int                     rescan_entered; /* used with nonremovable devices */
> > diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
> > index e9dfdd501cd1..4820e6d09dac 100644
> > --- a/include/linux/mmc/sdio_func.h
> > +++ b/include/linux/mmc/sdio_func.h
> > @@ -167,4 +167,7 @@ extern void sdio_f0_writeb(struct sdio_func *func, unsigned char b,
> >  extern mmc_pm_flag_t sdio_get_host_pm_caps(struct sdio_func *func);
> >  extern int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags);
> >
> > +extern void sdio_retune_crc_disable(struct sdio_func *func);
> > +extern void sdio_retune_crc_enable(struct sdio_func *func);
> > +
> >  #endif /* LINUX_MMC_SDIO_FUNC_H */
> > --
> > 2.22.0.rc2.383.gf4fbbf30c2-goog
> >
>
> Besides the minor comments, this looks good to me.

Thank you for the reviews!

I'll plan to send a v5 on my Monday with the fixes assuming no new
heated discussion starts up.  If it's less work for you, I'm also
happy if you just want to make the trivial fixes yourself when
applying.

-Doug

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