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 Fri, May 15, 2020 at 05:02:08PM +0200, Ulf Hansson wrote:
> On Fri, 15 May 2020 at 16:04, 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.
> 
> Just realized that part of the commit message is missing, explaining
> the change. I intend to add this:
> 
> 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().

Yeah, this paragraph is definately needed.

> Also, this is untested, so relying on you guys with the HW at hand.

I tested this on Gen3 M3-N (works fine!) and will next check your other
patch. If this is okay, too, I will check them on Gen2 tomorrow before I
give my Tested-by.

Ulf, thanks for working on this, too!


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