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

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Date:   Mon, 28 Feb 2022 18:03:59 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Ben Chuang <benchuanggli@...il.com>
Cc:     adrian.hunter@...el.com, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, greg.tu@...esyslogic.com.tw,
        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

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);
> +       }
> +       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?

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.

> +#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