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 <d4ff481f-1ed9-bd24-db9b-61e0479de12f@intel.com>
In-Reply-To: <d4ff481f-1ed9-bd24-db9b-61e0479de12f@intel.com>
From:   Baolin Wang <baolin.wang@linaro.org>
Date:   Mon, 11 Nov 2019 15:57:56 +0800
Message-ID: <CAMz4ku+7AVSyZzj0xYRT-rXAc4b=jPF98ekFuHbKYqZcCZxD-g@mail.gmail.com>
Subject: Re: [PATCH v6 4/4] mmc: host: sdhci: Add a variable to defer to
 complete requests if needed
To:     Adrian Hunter <adrian.hunter@intel.com>
Cc:     Ulf Hansson <ulf.hansson@linaro.org>, asutoshd@codeaurora.org,
        Orson Zhai <orsonzhai@gmail.com>,
        Chunyan Zhang <zhang.lyra@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Linus Walleij <linus.walleij@linaro.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        baolin.wang7@gmail.com, linux-mmc <linux-mmc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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On Mon, 11 Nov 2019 at 15:45, Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 11/11/19 9:34 AM, Baolin Wang wrote:
> > When using the host software queue, it will trigger the next request in
> > irq handler without a context switch. But the sdhci_request() can not be
> > called in interrupt context when using host software queue for some host
> > drivers, due to the get_cd() ops can be sleepable.
> >
> > But for some host drivers, such as Spreadtrum host driver, the card is
> > nonremovable, so the get_cd() ops is not sleepable, which means we can
> > complete the data request and trigger the next request in irq handler
> > to remove the context switch for the Spreadtrum host driver.
> >
> > Thus we still need introduce a variable in struct sdhci_host to indicate
> > that we will always to defer to complete requests if the sdhci_request()
> > can not be called in interrupt context for some host drivers, when using
> > the host software queue.
>
> Sorry, I assumed you would set host->always_defer_done in = true for the
> Spreadtrum host driver in patch "mmc: host: sdhci-sprd: Add software queue
> support" and put this patch before it.

Ah, sorry, I misunderstood your point.
So you still expect the Spreadtrum host driver should defer to
complete requests firstly, then introducing a request_atomic API in
next patch set to let our Spreadtrum host driver can call
request_atomic() in the interrupt context. OK, will do in next
version. Thanks.

> > Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
> > Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> > ---
> >  drivers/mmc/host/sdhci.c |    2 +-
> >  drivers/mmc/host/sdhci.h |    1 +
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 850241f..4bef066 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -3035,7 +3035,7 @@ static inline bool sdhci_defer_done(struct sdhci_host *host,
> >  {
> >       struct mmc_data *data = mrq->data;
> >
> > -     return host->pending_reset ||
> > +     return host->pending_reset || host->always_defer_done ||
> >              ((host->flags & SDHCI_REQ_USE_DMA) && data &&
> >               data->host_cookie == COOKIE_MAPPED);
> >  }
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index d89cdb9..a73ce89 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -533,6 +533,7 @@ struct sdhci_host {
> >       bool pending_reset;     /* Cmd/data reset is pending */
> >       bool irq_wake_enabled;  /* IRQ wakeup is enabled */
> >       bool v4_mode;           /* Host Version 4 Enable */
> > +     bool always_defer_done; /* Always defer to complete requests */
> >
> >       struct mmc_request *mrqs_done[SDHCI_MAX_MRQS];  /* Requests done */
> >       struct mmc_command *cmd;        /* Current command */
> >
>


-- 
Baolin Wang
Best Regards