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

[Ulf Hansson <ulf.hansson@linaro.org>]

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().

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

Kind regards
Uffe

>
> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>  drivers/mmc/host/tmio_mmc_core.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
> index f31afd1c2671..ba301fb7656b 100644
> --- a/drivers/mmc/host/tmio_mmc_core.c
> +++ b/drivers/mmc/host/tmio_mmc_core.c
> @@ -1231,12 +1231,14 @@ void tmio_mmc_host_remove(struct tmio_mmc_host *host)
>         cancel_work_sync(&host->done);
>         cancel_delayed_work_sync(&host->delayed_reset_work);
>         tmio_mmc_release_dma(host);
> +       tmio_mmc_disable_mmc_irqs(host, TMIO_MASK_ALL);
>
> -       pm_runtime_dont_use_autosuspend(&pdev->dev);
>         if (host->native_hotplug)
>                 pm_runtime_put_noidle(&pdev->dev);
> -       pm_runtime_put_sync(&pdev->dev);
> +
>         pm_runtime_disable(&pdev->dev);
> +       pm_runtime_dont_use_autosuspend(&pdev->dev);
> +       pm_runtime_put_noidle(&pdev->dev);
>  }
>  EXPORT_SYMBOL_GPL(tmio_mmc_host_remove);
>
> --
> 2.20.1
>