Better with the link.
On 05/07/2017 08:23, Quentin Schulz wrote:
> Hi Adrian and Ludovic,
>
> On 20/06/2017 11:49, Ludovic Desroches wrote:
>> On Tue, Jun 20, 2017 at 10:07:06AM +0200, Quentin Schulz wrote:
>>> Hi Adrian,
>>>
>>> On 20/06/2017 09:39, Adrian Hunter wrote:
>>>> On 16/06/17 10:29, Quentin Schulz wrote:
>>>>> This adds deepest (Backup+Self-Refresh) PM support to the ATMEL SAMA5D2
>>>>> SoC's SDHCI controller.
>>>>>
>>>>> When resuming from deepest state, it is required to restore preset
>>>>> registers as the registers are lost since VDD core has been shut down
>>>>> when entering deepest state on the SAMA5D2. The clocks need to be
>>>>> reconfigured as well.
>>>>>
>>>>> The other registers and init process are taken care of by the SDHCI
>>>>> core.
>>>>>
>>>>> Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>
>>>>> ---
>>>>> drivers/mmc/host/sdhci-of-at91.c | 34 ++++++++++++++++++++++++++++++++--
>>>>> 1 file changed, 32 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
>>>>> index fb8c6011f13d..300513fc1068 100644
>>>>> --- a/drivers/mmc/host/sdhci-of-at91.c
>>>>> +++ b/drivers/mmc/host/sdhci-of-at91.c
>>>>> @@ -207,6 +207,37 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
>>>>> }
>>>>>
>>>>> #ifdef CONFIG_PM
>>>>
>>>> Should be CONFIG_PM_SLEEP for suspend / resume callbacks.
>>>>
>>>
>>> So I let this CONFIG_PM around the runtime_suspend/resume but put
>>> another CONFIG_PM_SLEEP around the suspend/resume functions?
>>>
>>>>> +static int sdhci_at91_suspend(struct device *dev)
>>>>> +{
>>>>> + struct sdhci_host *host = dev_get_drvdata(dev);
>>>>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>>>> + struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
>>>>> + int ret;
>>>>> +
>>>>> + ret = sdhci_suspend_host(host);
>>>>> +
>>>>> + if (host->runtime_suspended)
>>>>> + return ret;
>>>>
>>>> Suspending while runtime suspended seems like a bad idea. Have you
>>>> considered just adding sdhci_at91_set_clks_presets() to
>>>> sdhci_at91_runtime_resume()?
>>>>
>>>
>>> Adding sdhci_at91_set_clks_presets() to runtime_resume() seems a bad
>>> idea as well. You don't need to recompute the clock rate, set it and set
>>> the presets registers each time you do a runtime_resume. As the
>>> runtime_pm of sdhci has a quite aggressive policy of activation, this
>>> seems like a bad idea on the optimization side.
>>
>> So maybe increment/decrement the device's usage counter. It should be
>> safer.
>>
>
> From what I've understood from the runtime_pm documentation[1], it seems
> that there is no need in my case to test if the system has been runtime
> suspended before being suspended. So I think we can safely remove the
> test and leave the rest as is.
>
> My understanding is the following:
> If the system is not runtime suspended before doing suspend, then it
> just does suspend and then resume.
> => enable and disable clocks are called once each so it is balanced.
>
> If the system is already runtime suspended when suspending, the resume
> will be called and once the device will be used, the runtime resume will
> be called.
> => enable and disable clocks are called twice each (once in runtime and
> system suspend/resume) so it is balanced.
>
> A few quick tests on my sama5d2_xplained seem to be validating those
> hypothesis.
>
> Do we agree on removing the `if (host->runtime_suspended)`?
>
[1]
http://elixir.free-electrons.com/linux/latest/source/Documentation/power/runtime_pm.txt#L613
> Thanks,
> Quentin
>
>> Ludovic
>>
>>>
>>> Thanks,
>>> Quentin
>>>
>>>>> +
>>>>> + clk_disable_unprepare(priv->gck);
>>>>> + clk_disable_unprepare(priv->hclock);
>>>>> + clk_disable_unprepare(priv->mainck);
>>>>> +
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +static int sdhci_at91_resume(struct device *dev)
>>>>> +{
>>>>> + struct sdhci_host *host = dev_get_drvdata(dev);
>>>>> + int ret;
>>>>> +
>>>>> + ret = sdhci_at91_set_clks_presets(dev);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + return sdhci_resume_host(host);
>>>>> +}
>>>>> +
>>>>> static int sdhci_at91_runtime_suspend(struct device *dev)
>>>>> {
>>>>> struct sdhci_host *host = dev_get_drvdata(dev);
>>>>> @@ -256,8 +287,7 @@ static int sdhci_at91_runtime_resume(struct device *dev)
>>>>> #endif /* CONFIG_PM */
>>>>>
>>>>> static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
>>>>> - SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
>>>>> - pm_runtime_force_resume)
>>>>> + SET_SYSTEM_SLEEP_PM_OPS(sdhci_at91_suspend, sdhci_at91_resume)
>>>>> SET_RUNTIME_PM_OPS(sdhci_at91_runtime_suspend,
>>>>> sdhci_at91_runtime_resume,
>>>>> NULL)
>>>>>
>>>>
>>>
>>> --
>>> Quentin Schulz, Free Electrons
>>> Embedded Linux and Kernel engineering
>>> http://free-electrons.com
>
--
Quentin Schulz, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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