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

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Message-ID: <4b35e465-626a-7218-ed9a-4e5cf28c1ccc@intel.com>
Date:   Tue, 1 Mar 2022 12:05:17 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Ben Chuang <benchuanggli@...il.com>
Cc:     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 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);
	}


>> +       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.

Assuming the host controller does not lose state information, it should be fine.

> 
>> +#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