23.01.2020 12:22, Sameer Pujar пишет: > > > On 1/22/2020 9:57 PM, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 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. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel