linux-kernel - Re: [PATCH] mmc: sdhci-pci-gli: Add runtime PM for GL9763E

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Date:   Wed, 2 Mar 2022 10:10:37 +0800
From:   Ben Chuang <benchuanggli@...il.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        greg.tu@...esyslogic.com.tw,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>,
        SeanHY.Chen@...esyslogic.com.tw,
        Kevin Chang <kevin.chang@...uturecenter.com>
Subject: Re: [PATCH] mmc: sdhci-pci-gli: Add runtime PM for GL9763E

Hi,

On Tue, Mar 1, 2022 at 6:05 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 28/02/2022 19:03, Ulf Hansson wrote:
> > On Fri, 25 Feb 2022 at 13:56, Ben Chuang <benchuanggli@...il.com> wrote:
> >>
> >> From: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> >>
> >> Add runtime PM for GL9763E and disable PLL in runtime suspend. So power
> >> gated of upstream port can be enabled.
> >>
> >> Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> >> Tested-by: Kevin Chang <kevin.chang@...uturecenter.com>
> >> ---
> >>  drivers/mmc/host/sdhci-pci-gli.c | 54 ++++++++++++++++++++++++++++++++
> >>  1 file changed, 54 insertions(+)
> >>
> >> diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
> >> index 97035d77c18c..cf99b6af792d 100644
> >> --- a/drivers/mmc/host/sdhci-pci-gli.c
> >> +++ b/drivers/mmc/host/sdhci-pci-gli.c
> >> @@ -873,6 +873,55 @@ static void gli_set_gl9763e(struct sdhci_pci_slot *slot)
> >>         pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> >>  }
> >>
> >> +#ifdef CONFIG_PM
> >> +static int gl9763e_runtime_suspend(struct sdhci_pci_chip *chip)
> >> +{
> >> +       struct sdhci_pci_slot *slot = chip->slots[0];
> >> +       struct sdhci_host *host = slot->host;
> >> +       u16 clock;
> >> +
> >> +       clock = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> >> +       clock &= ~(SDHCI_CLOCK_PLL_EN | SDHCI_CLOCK_CARD_EN);
> >> +       sdhci_writew(host, clock, SDHCI_CLOCK_CONTROL);
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static int gl9763e_runtime_resume(struct sdhci_pci_chip *chip)
> >> +{
> >> +       struct sdhci_pci_slot *slot = chip->slots[0];
> >> +       struct sdhci_host *host = slot->host;
> >> +       ktime_t timeout;
> >> +       u16 clock;
> >> +
> >> +       clock = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> >> +
> >> +       clock |= SDHCI_CLOCK_PLL_EN;
> >> +       clock &= ~SDHCI_CLOCK_INT_STABLE;
> >> +       sdhci_writew(host, clock, SDHCI_CLOCK_CONTROL);
> >> +
> >> +       timeout = ktime_add_ms(ktime_get(), 150);
> >> +       while (1) {
> >> +               bool timedout = ktime_after(ktime_get(), timeout);
> >> +
> >> +               clock = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> >> +               if (clock & SDHCI_CLOCK_INT_STABLE)
> >> +                       break;
> >> +               if (timedout) {
> >> +                       pr_err("%s: PLL clock never stabilised.\n",
> >> +                              mmc_hostname(host->mmc));
> >> +                       sdhci_dumpregs(host);
> >> +                       break;
> >> +               }
> >> +               udelay(10);
> >> +       }
>
> Could use something like read_poll_timeout() here e.g.
>
>         if (read_poll_timeout(sdhci_readw, clk, (clk & SDHCI_CLOCK_INT_STABLE),
>                               1000, 150000, false, host, SDHCI_CLOCK_CONTROL)) {
>                 pr_err("%s: PLL clock never stabilised.\n",
>                        mmc_hostname(host->mmc));
>                 sdhci_dumpregs(host);
>         }
>
>

Thanks for the tip. I will prepare the next patch.

> >> +       clock |= SDHCI_CLOCK_CARD_EN;
> >> +       sdhci_writew(host, clock, SDHCI_CLOCK_CONTROL);
> >> +
> >> +       return 0;
> >> +}
> >
> > Both functions above look very similar to what sdhci_set_clock() does.
> > Can you use that, rather than open coding the above?
> >

The codes turn on/off the clock but it doesn't change the clock.
Using sdhci_set_clock()  needs to store the clock value because it
clears the clock.

> > Other than that, I would appreciate it if Adrian could have a look at
> > this too. For example, I wonder if perhaps
> > sdhci_runtime_suspend|resume_host() should be called in these paths
> > too.
>
> Assuming the host controller does not lose state information, it should be fine.
>

Yes, the host always has aux. power and keep state.

Thank you both for your comments.

> >
> >> +#endif
> >> +
> >>  static int gli_probe_slot_gl9763e(struct sdhci_pci_slot *slot)
> >>  {
> >>         struct pci_dev *pdev = slot->chip->pdev;
> >> @@ -982,6 +1031,11 @@ const struct sdhci_pci_fixes sdhci_gl9763e = {
> >>  #ifdef CONFIG_PM_SLEEP
> >>         .resume         = sdhci_cqhci_gli_resume,
> >>         .suspend        = sdhci_cqhci_gli_suspend,
> >> +#endif
> >> +#ifdef CONFIG_PM
> >> +       .runtime_suspend = gl9763e_runtime_suspend,
> >> +       .runtime_resume  = gl9763e_runtime_resume,
> >> +       .allow_runtime_pm = true,
> >>  #endif
> >>         .add_host       = gl9763e_add_host,
> >>  };
> >> --
> >> 2.35.1
> >>
> >
> > Kind regards
> > Uffe
>

Best regards,
Ben