Re: [PATCH] mmc: tmio: Fix hang during suspend

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Ulf,

On Mon, Aug 18, 2014 at 3:10 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On 18 August 2014 14:36, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>> On Fri, Aug 15, 2014 at 2:49 PM, Ian Molton <ian.molton@codethink.co.uk> wrote:
>>> On Thu, 14 Aug 2014 17:23:53 +0200
>>> Geert Uytterhoeven <geert+renesas@glider.be> wrote:
>>>> On R-Car Gen 2, the SDHI registers cannot be accessed while the SDHI
>>>> module clock is disabled. Doing so will cause a lock-up.
>>>>
>>>> When suspending, enable the module clock before disabling the SDHI
>>>> interrupts, and disable the clock again afterwards.
>>>
>>> This feels wrong. Why can't interrupts be disabled prior to turning the clock off?
>>
>> The clock is handled by runtime PM. So if SDHI becomes idle, the clock
>> is turned off.
>> However, the card insertion interrupt is still enabled.
>> If all interrupts would be disabled when the clock is turned off, I believe card
>> insertion can no longer be detected.
>>
>> BTW, I'm still wondering why tmio_mmc_host_resume() works without
>> enabling the clock, as it calls tmio_mmc_enable_dma(), which also writes to
>> an SDHI register (CTL_DMA_ENABLE).
>
> A while ago, I tried to rework the runtime PM handling of tmio.
>
> http://www.spinics.net/lists/linux-mmc/msg23177.html
>
> The hole set never got merged, due to that we couldn't get them tested
> on hardware and there were a lack in review.
>
> We might want to pick them up to see if those may solve our problem. :-)

Thanks, I applied patches 4-8 (1-3 did get merged), and tried them on
SDHI1 of r8a7791/koelsch. It still seems to work as before.

However, I still need my patch to fix suspend.
Your "[PATCH 8/8] mmc: tmio: Handle clock gating from runtime PM functions"
manages the SDHI interface clock, while my patch manages the platform-specific
SDHI module clock.

>>>> This fixes suspend and resume on r8a7791/koelsch.
>>>>
>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>>>> ---
>>>>  drivers/mmc/host/tmio_mmc_pio.c | 10 ++++++++++
>>>>  1 file changed, 10 insertions(+)
>>>>
>>>> diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
>>>> index faf0924e71cb..83192420a7e3 100644
>>>> --- a/drivers/mmc/host/tmio_mmc_pio.c
>>>> +++ b/drivers/mmc/host/tmio_mmc_pio.c
>>>> @@ -1147,8 +1147,18 @@ int tmio_mmc_host_suspend(struct device *dev)
>>>>  {
>>>>       struct mmc_host *mmc = dev_get_drvdata(dev);
>>>>       struct tmio_mmc_host *host = mmc_priv(mmc);
>>>> +     struct tmio_mmc_data *pdata = host->pdata;
>>>> +
>>>> +     if (pdata->clk_enable) {
>>>> +             unsigned int f;
>>>> +             pdata->clk_enable(host->pdev, &f);
>>>> +     }
>>>>
>>>>       tmio_mmc_disable_mmc_irqs(host, TMIO_MASK_ALL);
>>>> +
>>>> +     if (pdata->clk_disable)
>>>> +             pdata->clk_disable(host->pdev);
>>>> +
>>>>       return 0;
>>>>  }
>>>>  EXPORT_SYMBOL(tmio_mmc_host_suspend);

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds