linux-kernel - Re: [PATCH v2] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming

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Date:   Tue, 16 Jul 2019 16:28:52 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: host: sdhci-sprd: Fix the incorrect soft reset
 operation when runtime resuming

On Tue, 16 Jul 2019 at 16:24, Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 16/07/19 10:31 AM, Baolin Wang wrote:
> > In sdhci_runtime_resume_host() function, we will always do software reset
> > for all, which will cause Spreadtrum host controller work abnormally after
> > resuming.
> >
> > Thus for Spreadtrum platform that do not power down the SD/eMMC card during
> > runtime suspend, we should not do software reset for all. To fix this
> > issue, adding a specific reset operation that add one condition to validate
> > the MMC_CAP_AGGRESSIVE_PM to decide if we can do software reset for all or
> > just reset command and data lines.
> >
> > Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> > ---
> > Changes from v1:
> >  - Add a specific reset operation instead of changing the core to avoid
> >  affecting other hardware.
> > ---
> >  drivers/mmc/host/sdhci-sprd.c |   38 +++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 37 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c
> > index 603a5d9..174b566 100644
> > --- a/drivers/mmc/host/sdhci-sprd.c
> > +++ b/drivers/mmc/host/sdhci-sprd.c
> > @@ -373,6 +373,42 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
> >       return 1 << 31;
> >  }
> >
> > +static void sdhci_sprd_reset(struct sdhci_host *host, u8 mask)
> > +{
> > +     struct mmc_host *mmc = host->mmc;
> > +     ktime_t timeout;
> > +
> > +     /*
> > +      * When try to reset controller after runtime suspend, we should not
> > +      * reset for all if the SD/eMMC card is not power down, just reset
> > +      * command and data lines instead. Otherwise will meet some strange
> > +      * behaviors for Spreadtrum host controller.
> > +      */
> > +     if (host->runtime_suspended && (mask & SDHCI_RESET_ALL) &&
> > +         !(mmc->caps & MMC_CAP_AGGRESSIVE_PM))
> > +             mask = SDHCI_RESET_CMD | SDHCI_RESET_DATA;
> > +
>
> Here you could just call sdhci_reset(host, mask) instead of below.

Ah, right. Thanks for your comment.

>
> > +     sdhci_writeb(host, mask, SDHCI_SOFTWARE_RESET);
> > +
> > +     /* Wait max 100 ms */
> > +     timeout = ktime_add_ms(ktime_get(), 100);
> > +
> > +     /* hw clears the bit when it's done */
> > +     while (1) {
> > +             bool timedout = ktime_after(ktime_get(), timeout);
> > +
> > +             if (!(sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask))
> > +                     break;
> > +             if (timedout) {
> > +                     pr_err("%s: Reset 0x%x never completed.\n",
> > +                             mmc_hostname(host->mmc), (int)mask);
> > +                     sdhci_dumpregs(host);
> > +                     return;
> > +             }
> > +             udelay(10);
> > +     }
> > +}
> > +
> >  static struct sdhci_ops sdhci_sprd_ops = {
> >       .read_l = sdhci_sprd_readl,
> >       .write_l = sdhci_sprd_writel,
> > @@ -381,7 +417,7 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
> >       .get_max_clock = sdhci_sprd_get_max_clock,
> >       .get_min_clock = sdhci_sprd_get_min_clock,
> >       .set_bus_width = sdhci_set_bus_width,
> > -     .reset = sdhci_reset,
> > +     .reset = sdhci_sprd_reset,
> >       .set_uhs_signaling = sdhci_sprd_set_uhs_signaling,
> >       .hw_reset = sdhci_sprd_hw_reset,
> >       .get_max_timeout_count = sdhci_sprd_get_max_timeout_count,
> >
>


-- 
Baolin Wang
Best Regards