linux-kernel - Re: [PATCH 05/11] mmc: core: Clarify sdio_irq_pending flag for MMC_CAP2_SDIO_IRQ

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Date:   Thu, 5 Sep 2019 09:29:48 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Douglas Anderson <dianders@...omium.org>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Jaehoon Chung <jh80.chung@...sung.com>,
        Yong Mao <yong.mao@...iatek.com>,
        Chaotian Jing <chaotian.jing@...iatek.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 05/11] mmc: core: Clarify sdio_irq_pending flag for MMC_CAP2_SDIO_IRQ_NOTHREAD

On Thu, 5 Sep 2019 at 02:34, Matthias Kaehlcke <mka@...omium.org> wrote:
>
> On Tue, Sep 03, 2019 at 04:22:01PM +0200, Ulf Hansson wrote:
> > In the single SDIO IRQ handler case, the sdio_irq_pending flag is used to
> > avoid reading the SDIO_CCCR_INTx register and instead immediately call the
> > SDIO func's >irq_handler() callback.
> >
> > To clarify the use behind the flag for the MMC_CAP2_SDIO_IRQ_NOTHREAD case,
> > let's set the flag from inside sdio_signal_irq(), rather from
> > sdio_run_irqs(). Moreover, let's also reset the flag when the SDIO IRQ have
> > been properly processed.
> >
> > Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> > ---
> >  drivers/mmc/core/sdio_irq.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
> > index f75043266984..0962a4357d54 100644
> > --- a/drivers/mmc/core/sdio_irq.c
> > +++ b/drivers/mmc/core/sdio_irq.c
> > @@ -59,6 +59,7 @@ static int process_sdio_pending_irqs(struct mmc_host *host)
> >  {
> >       struct mmc_card *card = host->card;
> >       int i, ret, count;
> > +     bool sdio_irq_pending = host->sdio_irq_pending;
> >       unsigned char pending;
> >       struct sdio_func *func;
> >
> > @@ -66,13 +67,16 @@ static int process_sdio_pending_irqs(struct mmc_host *host)
> >       if (mmc_card_suspended(card))
> >               return 0;
> >
> > +     /* Clear the flag to indicate that we have processed the IRQ. */
> > +     host->sdio_irq_pending = false;
> > +
>
> It's not entirely true that we have processed the IRQ,
> the sdio_get_pending_irqs() below could fail and we'd return. However
> I guess if it comes to that we are in a pretty bad shape already and
> the value of the flag doesn't really matter.

Yes, that's my view as well.

>
> >       /*
> >        * Optimization, if there is only 1 function interrupt registered
> >        * and we know an IRQ was signaled then call irq handler directly.
> >        * Otherwise do the full probe.
> >        */
> >       func = card->sdio_single_irq;
> > -     if (func && host->sdio_irq_pending) {
> > +     if (func && sdio_irq_pending) {
> >               func->irq_handler(func);
> >               return 1;
> >       }
> > @@ -110,7 +114,6 @@ static void sdio_run_irqs(struct mmc_host *host)
> >  {
> >       mmc_claim_host(host);
> >       if (host->sdio_irqs) {
> > -             host->sdio_irq_pending = true;
> >               process_sdio_pending_irqs(host);
> >               if (host->ops->ack_sdio_irq)
> >                       host->ops->ack_sdio_irq(host);
> > @@ -128,6 +131,7 @@ void sdio_irq_work(struct work_struct *work)
> >
> >  void sdio_signal_irq(struct mmc_host *host)
> >  {
> > +     host->sdio_irq_pending = true;
> >       queue_delayed_work(system_wq, &host->sdio_irq_work, 0);
> >  }
> >  EXPORT_SYMBOL_GPL(sdio_signal_irq);
> > @@ -173,7 +177,6 @@ static int sdio_irq_thread(void *_host)
> >               if (ret)
> >                       break;
> >               ret = process_sdio_pending_irqs(host);
> > -             host->sdio_irq_pending = false;
> >               mmc_release_host(host);
> >
> >               /*
>
> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>

Thanks!

Kind regards
Uffe