[PATCH v3 2/3] mmc: sdhci-of-dwcmshc: Add runtime PM support

[Shawn Lin]

Hi Ulf,

On 2023/2/14 7:45, Ulf Hansson wrote:
> On Thu, 2 Feb 2023 at 01:35, Shawn Lin <shawn.lin at rock-chips.com> wrote:
>>
>> This patch adds runtime PM support.
>>
>> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
>> ---
>>
>> Changes in v2: None
>>
>>   drivers/mmc/host/sdhci-of-dwcmshc.c | 51 ++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 50 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
>> index 46b1ce7..fc917ed 100644
>> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
>> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
>> @@ -15,6 +15,7 @@
>>   #include <linux/module.h>
>>   #include <linux/of.h>
>>   #include <linux/of_device.h>
>> +#include <linux/pm_runtime.h>
>>   #include <linux/reset.h>
>>   #include <linux/sizes.h>
>>
>> @@ -551,6 +552,13 @@ static int dwcmshc_probe(struct platform_device *pdev)
>>          if (err)
>>                  goto err_setup_host;
>>
>> +       pm_runtime_get_noresume(&pdev->dev);
>> +       pm_runtime_set_active(&pdev->dev);
>> +       pm_runtime_enable(&pdev->dev);
>> +       pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
>> +       pm_runtime_use_autosuspend(&pdev->dev);
>> +       pm_runtime_put_autosuspend(&pdev->dev);
>> +
>>          return 0;
>>
>>   err_setup_host:
>> @@ -580,6 +588,11 @@ static int dwcmshc_remove(struct platform_device *pdev)
>>          if (rk_priv)
>>                  clk_bulk_disable_unprepare(RK35xx_MAX_CLKS,
>>                                             rk_priv->rockchip_clks);
>> +
>> +       pm_runtime_get_sync(&pdev->dev);
>> +       pm_runtime_disable(&pdev->dev);
>> +       pm_runtime_put_noidle(&pdev->dev);
>> +
>>          sdhci_pltfm_free(pdev);
>>
>>          return 0;
>> @@ -638,7 +651,43 @@ static int dwcmshc_resume(struct device *dev)
>>   }
>>   #endif
>>
>> -static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend, dwcmshc_resume);
>> +#ifdef CONFIG_PM
>> +static int dwcmshc_runtime_suspend(struct device *dev)
>> +{
>> +       struct sdhci_host *host = dev_get_drvdata(dev);
>> +       u16 data;
>> +       int ret;
>> +
>> +       ret = sdhci_runtime_suspend_host(host);
>> +       if (ret)
>> +               return ret;
>> +
>> +       data = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
>> +       data &= ~SDHCI_CLOCK_CARD_EN;
>> +       sdhci_writew(host, data, SDHCI_CLOCK_CONTROL);
>> +
>> +       return 0;
>> +}
>> +
>> +static int dwcmshc_runtime_resume(struct device *dev)
>> +{
>> +       struct sdhci_host *host = dev_get_drvdata(dev);
>> +       u16 data;
>> +
>> +       data = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
>> +       data |= SDHCI_CLOCK_CARD_EN;
>> +       sdhci_writew(host, data, SDHCI_CLOCK_CONTROL);
>> +
>> +       return sdhci_runtime_resume_host(host, 0);
>> +}
>> +#endif
>> +
>> +static const struct dev_pm_ops dwcmshc_pmops = {
>> +       SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend,
>> +                               dwcmshc_resume)
> 
> I have looked at dwcmshc_suspend(), which calls sdhci_suspend_host().
> As sdhci_suspend_host() will write to internal registers of the IP
> block, it's recommended to make sure the device's runtime resumed
> before doing that call. So that needs to be added along with $subject
> patch.
> 

Yep, let me add a check here.

> There is also another option that may better for you, which is to use
> the pm_runtime_force_suspend|resume() helpers. There should be plenty
> of references to look at, but don't hesitate to ask around that, if
> you need some more help to get that working.

If I understand correctly,  pm_runtime_force_suspend|resume() helpers
would use runtime PM ops for suspend/resume routine. In this case, the
main issue is the handling of clock is quite different. In suspend we
need to gate all clocks but in rpm case, it shouldn't.


> 
>> +       SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
>> +                          dwcmshc_runtime_resume, NULL)
>> +};
>>
>>   static struct platform_driver sdhci_dwcmshc_driver = {
>>          .driver = {
> 
> Kind regards
> Uffe