On 23/01/2020 15:16, Dmitry Osipenko wrote:
23.01.2020 12:22, Sameer Pujar пишет:
On 1/22/2020 9:57 PM, Dmitry Osipenko wrote:
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22.01.2020 14:52, Jon Hunter пишет:
On 22/01/2020 07:16, Sameer Pujar wrote:
...
>>>>> +static int tegra210_i2s_remove(struct platform_device *pdev) >>>>> +{ >>>>> + pm_runtime_disable(&pdev->dev); >>>>> + if (!pm_runtime_status_suspended(&pdev->dev)) >>>>> + tegra210_i2s_runtime_suspend(&pdev->dev); >>>> This breaks device's RPM refcounting if it was disabled in the >>>> active >>>> state. This code should be removed. At most you could warn >>>> about the >>>> unxpected RPM state here, but it shouldn't be necessary. >>> I guess this was added for safety and explicit suspend keeps clock >>> disabled. >>> Not sure if ref-counting of the device matters when runtime PM is >>> disabled and device is removed. >>> I see few drivers using this way. >> It should matter (if I'm not missing something) because RPM should >> be in >> a wrecked state once you'll try to re-load the driver's module. >> Likely >> that those few other drivers are wrong. >> >> [snip] > Once the driver is re-loaded and RPM is enabled, I don't think it > would use > the same 'dev' and the corresponding ref count. Doesn't it use the > new > counters? > If RPM is not working for some reason, most likely it would be the > case > for other > devices. What best driver can do is probably do a force suspend > during > removal if > already not done. I would prefer to keep, since multiple drivers > still > have it, > unless there is a real harm in doing so. I took a closer look and looks like the counter actually should be reset. Still I don't think that it's a good practice to make changes underneath of RPM, it may strike back.
If RPM is broken, it probably would have been caught during device usage. I will remove explicit suspend here if no any concerns from other folks. Thanks.
I recall that this was the preferred way of doing this from the RPM folks. Tegra30 I2S driver does the same and Stephen had pointed me to this as a reference. I believe that this is meant to ensure that the device is always powered-off regardless of it RPM is enabled or not and what the current state is.
Yes, it was kinda actual for the case of unavailable RPM.
Anyways, /I think/ variant like this should have been more preferred:
if (!pm_runtime_enabled(&pdev->dev)) tegra210_i2s_runtime_suspend(&pdev->dev); else pm_runtime_disable(&pdev->dev);
I think it looks to be similar to what is there already.
pm_runtime_disable(&pdev->dev); // it would turn out to be a dummy call if !RPM if (!pm_runtime_status_suspended(&pdev->dev)) // it is true always if !RPM tegra210_i2s_runtime_suspend(&pdev->dev);
Maybe this is fine for !RPM, but not really fine in a case of enabled RPM. Device could be in resumed state after pm_runtime_disable() if it wasn't suspended before the disabling.
I don't see any problem with this for the !RPM case.
Jon