Re: [PATCH 1/2] mmc: tmio: Further fixup runtime PM management at remove

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

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On Wed, May 20, 2020 at 04:30:33PM +0200, Geert Uytterhoeven wrote:
> Hi Ulf,
> 
> On Tue, May 19, 2020 at 5:24 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > Before calling tmio_mmc_host_probe(), the caller is required to enable
> > clocks for its device, as to make it accessible when reading/writing
> > registers during probe.
> >
> > Therefore, the responsibility to disable these clocks, in the error path of
> > ->probe() and during ->remove(), is better managed outside
> > tmio_mmc_host_remove(). As a matter of fact, callers of
> > tmio_mmc_host_remove() already expects this to be the behaviour.
> >
> > However, there's a problem with tmio_mmc_host_remove() when the Kconfig
> > option, CONFIG_PM, is set. More precisely, tmio_mmc_host_remove() may then
> > disable the clock via runtime PM, which leads to clock enable/disable
> > imbalance problems, when the caller of tmio_mmc_host_remove() also tries to
> > disable the same clocks.
> >
> > To solve the problem, let's make sure tmio_mmc_host_remove() leaves the
> > device with clocks enabled, but also make sure to disable the IRQs, as we
> > normally do at ->runtime_suspend().
> >
> > Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> > Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> 
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> 
> (on R-Car Gen2, various Gen3, SH-Mobile AG5, R-Mobile A1, R-Mobile APE6,
>  RZ/A1, and RZ/A2)

Thanks, Geert! If it is not too much to ask, could you try re-applying
commit 7a7dab237027 ("mmc: tmio: remove workaround for NON_REMOVABLE")
on top of all these patches and see if your NFS is still stalled?

Sidenote: we still need to tackle the problem when SCC hangs because it
has no clock. However, I am still interested if all the PM updates have
an impact in the beaviour you observed here[1].

[1] https://patchwork.kernel.org/patch/11149285/


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