linux-kernel - Re: [PATCH 05/17] mmc: mmci: Put the device into low power state at system suspend

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Date:	Mon, 10 Feb 2014 10:03:57 -0800
From:	Kevin Hilman <khilman@...aro.org>
To:	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Russell King <linux@....linux.org.uk>,
	"linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Alessandro Rubini <rubini@...pv.it>,
	Linus Walleij <linus.walleij@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Chris Ball <chris@...ntf.net>, Mark Brown <broonie@...nel.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-i2c\@vger.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-spi\@vger.kernel.org" <linux-spi@...r.kernel.org>,
	linux-mmc <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH 05/17] mmc: mmci: Put the device into low power state at system suspend

Ulf Hansson <ulf.hansson@...aro.org> writes:

> On 4 February 2014 20:22, Kevin Hilman <khilman@...aro.org> wrote:
>> Ulf Hansson <ulf.hansson@...aro.org> writes:
>>
>>> Due to the available runtime PM callbacks, we are now able to put our
>>> device into low power state at system suspend.
>>>
>>> Earlier we could not accomplish this without trusting a power domain
>>> for the device to take care of it. Now we are able to cope with
>>> scenarios both with and without a power domain.
>>>
>>> Cc: Russell King <linux@....linux.org.uk>
>>> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
>>> ---
>>>  drivers/mmc/host/mmci.c |   45 +++++++++++++++++++++++++--------------------
>>>  1 file changed, 25 insertions(+), 20 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
>>> index c88da1c..074e0cb 100644
>>> --- a/drivers/mmc/host/mmci.c
>>> +++ b/drivers/mmc/host/mmci.c
>>> @@ -1723,33 +1723,38 @@ static int mmci_remove(struct amba_device *dev)
>>>       return 0;
>>>  }
>>>
>>> -#ifdef CONFIG_SUSPEND
>>> -static int mmci_suspend(struct device *dev)
>>> +#ifdef CONFIG_PM_SLEEP
>>> +static int mmci_suspend_late(struct device *dev)
>>>  {
>>> -     struct amba_device *adev = to_amba_device(dev);
>>> -     struct mmc_host *mmc = amba_get_drvdata(adev);
>>> +     int ret = 0;
>>>
>>> -     if (mmc) {
>>> -             struct mmci_host *host = mmc_priv(mmc);
>>> -             pm_runtime_get_sync(dev);
>>> -             writel(0, host->base + MMCIMASK0);
>>> -     }
>>> +     if (pm_runtime_status_suspended(dev))
>>> +             return 0;
>>>
>>> -     return 0;
>>> +     if (dev->pm_domain && dev->pm_domain->ops.runtime_suspend)
>>> +             ret = dev->pm_domain->ops.runtime_suspend(dev);
>>> +     else
>>> +             ret = dev->bus->pm->runtime_suspend(dev);
>>> +
>>> +     if (!ret)
>>> +             pm_runtime_set_suspended(dev);
>>
>> Isn't this basically open-coding pm_runtime_suspend()...
>
> It is similar, but with once big difference.
>
> Since the PM core prevents pm_runtime_suspend() from invoking our
> ->runtime_suspend callback during system suspend (it does so by
> invoking pm_runtime_get_sync() before starting the suspend sequence),
> we then need to make the driver handle that by itself.

Yeah, I still think we need to allow a bus/pm_domain to override that
behavior.


Kevin
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