linux-kernel - Re: [PATCH] mmc: sdhci-of-at91: fix wakeup issue when using runtime pm

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Date:	Fri, 4 Mar 2016 10:12:20 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Ludovic Desroches <ludovic.desroches@...el.com>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Nicolas Ferre <nicolas.ferre@...el.com>
Subject: Re: [PATCH] mmc: sdhci-of-at91: fix wakeup issue when using runtime pm

+ Ludovic

On 4 March 2016 at 10:09, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> On 17 February 2016 at 11:35, Ludovic Desroches
> <ludovic.desroches@...el.com> wrote:
>> On Tue, Feb 16, 2016 at 04:22:04PM +0100, Ludovic Desroches wrote:
>>> On Tue, Feb 16, 2016 at 03:38:29PM +0100, Ulf Hansson wrote:
>>> > On 13 February 2016 at 10:56, Ludovic Desroches
>>> > <ludovic.desroches@...el.com> wrote:
>>> > > When suspending the sdhci host, the only hardware event that could wake
>>> > > up the host is a sdio irq if they are enabled. If we want to wakeup on
>>> > > card detect events, a gpio as to be used.
>>> > > If we don't want to use a gpio but the card detect pio of the controller
>>> > > then we need to keep enabled the clock of the controller interface to
>>> > > get the interrupt and to not set the host in a suspended state to have the
>>> > > interrupt handled.
>>> > >
>>> > > Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
>>> > > ---
>>> > >  drivers/mmc/host/sdhci-of-at91.c | 46 ++++++++++++++++++++++++++++++----------
>>> > >  1 file changed, 35 insertions(+), 11 deletions(-)
>>> > >
>>> > > diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
>>> > > index efec736..2159c6e 100644
>>> > > --- a/drivers/mmc/host/sdhci-of-at91.c
>>> > > +++ b/drivers/mmc/host/sdhci-of-at91.c
>>> > > @@ -18,6 +18,7 @@
>>> > >  #include <linux/err.h>
>>> > >  #include <linux/io.h>
>>> > >  #include <linux/mmc/host.h>
>>> > > +#include <linux/mmc/slot-gpio.h>
>>> > >  #include <linux/module.h>
>>> > >  #include <linux/of.h>
>>> > >  #include <linux/of_device.h>
>>> > > @@ -45,7 +46,6 @@ static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
>>> > >
>>> > >  static const struct sdhci_pltfm_data soc_data_sama5d2 = {
>>> > >         .ops = &sdhci_at91_sama5d2_ops,
>>> > > -       .quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION,
>>> >
>>> > You probably have some leftovers from earlier local changes, as this
>>> > isn't going to apply to my next branch.
>>> >
>>>
>>> Yes, it is based on the first patch of this thread, it was only to
>>> discuss about it.
>>>
>>> > >         .quirks2 = SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST,
>>> > >  };
>>> > >
>>> > > @@ -55,17 +55,37 @@ static const struct of_device_id sdhci_at91_dt_match[] = {
>>> > >  };
>>> > >
>>> > >  #ifdef CONFIG_PM
>>> > > +static bool sdhci_at91_use_sdhci_runtime(struct sdhci_host *host)
>>> > > +{
>>> > > +       u32 caps = host->mmc->caps;
>>> > > +
>>> > > +       return (caps & MMC_CAP_NONREMOVABLE) ||
>>> > > +              (!IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc)));
>>
>>
>> I am wondering if I should take account of sdio irq enabled or not here.
>>
>> I have a sdio device which drives me crazy because of power management.
>> The driver of this device is in staging, it is wilc1000. It seems that I
>> am stuck because the sdio irq are not received. If I don't disable the
>> clock of the controller (hclock), I should receive the sdio IRQ as I
>> receive card detect ones, isn't it?
>>
>> It doesn't work, it seems I have also to not disabled mainck and gck
>> which are clocks needed to generate the clock sent to the sdio device.
>> If none of the clocks have to be disabled, where it has to be managed?
>
> That's a typical issue for SDIO IRQs, especially when the controller
> HW manages IRQs (there are other ways to deal with SDIO IRQs as well).
>
> Currently, the simplest way to deal with this in the driver is to do a
> pm_runtime_get_sync() when the SDIO IRQ gets enabled, and
> pm_runtime_put() when it gets disabled.
>
>>
>> Do I have to anticipate this use case in the driver of my sdhci
>> controller or does it have to be managed in the sdio device driver? They
>> are using sdio_claim/release_host to suspend or resume the host but
>> maybe they use it in a bad way.
>
> The wilc100 SDIO func driver should *not* keep the host claimed to
> deal with SDIO irqs. Only when it configures them.
>
> Instead, you need to deal with this in the sdhci driver, when you get
> the call to enable/disable SDIO IRQs.
>
> Moreover, from a system PM point of view. If the wilc100 SDIO func
> driver wants the platform to wake up on SDIO IRQs, it needs to set
> MMC_PM_KEEP_POWER and MMC_PM_WAKE_SDIO_IRQ from its ->suspend()
> callback.
>
> In that way, your sdhci driver can act accordingly from its system PM
> callbacks. In other words, depending on MMC_PM_KEEP_POWER and
> MMC_PM_WAKE_SDIO_IRQ to *not* call pm_runtime_force_suspend().
>
> [...]
>
> Kind regards
> Uffe