Re: [PATCH 1/1] mmc: mmci: add threaded irq to abort DPSM of non-functional state

[Ludovic BARRE]

hi Ulf

Le 12/10/19 Ã 1:30 PM, Ulf Hansson a ÃcritÂ:
> On Wed, 13 Nov 2019 at 18:25, Ludovic Barre <ludovic.Barre@xxxxxx> wrote:
> > From: Ludovic Barre <ludovic.barre@xxxxxx>
> >
> > If datatimeout occurs on R1B request, the Data Path State Machine stays
> > in busy and is non-functional. Only a reset aborts the DPSM.
> >
> > Like a reset must be outside of critical section, this patch adds
> > threaded irq function to release state machine. In this case,
> > the mmc_request_done is called at the end of threaded irq and
> > skipped into irq handler.
> >
> > Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx>
> > ---
> >   drivers/mmc/host/mmci.c | 44 ++++++++++++++++++++++++++++++++++++-----
> >   drivers/mmc/host/mmci.h |  1 +
> >   2 files changed, 40 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> > index 40e72c30ea84..ec6e249c87ca 100644
> > --- a/drivers/mmc/host/mmci.c
> > +++ b/drivers/mmc/host/mmci.c
> > @@ -556,6 +556,9 @@ static void mmci_dma_error(struct mmci_host *host)
> >   static void
> >   mmci_request_end(struct mmci_host *host, struct mmc_request *mrq)
> >   {
> > +       if (host->irq_action == IRQ_WAKE_THREAD)
> > +               return;
> > +
>
> It seems a bit unnecessary to check this every time mmci_request_end()
> is called.
>
> How about avoiding to call mmci_request_end() for the one specific
> condition instead? See more below.
>
> >          writel(0, host->base + MMCICOMMAND);
> >
> >          BUG_ON(host->data);
> > @@ -1321,6 +1324,7 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
> >          } else if (host->variant->busy_timeout && busy_resp &&
> >                     status & MCI_DATATIMEOUT) {
> >                  cmd->error = -ETIMEDOUT;
> > +               host->irq_action = IRQ_WAKE_THREAD;
>
> You could check this flag a few lines below and if it's set to
> IRQ_WAKE_THREAD, avoid to call mmci_request_end().

yes, it was my first implementation. after, I wanted to centralize this,
if the irq threaded would be extend.
But you are right, it's not the goal of this commit.

I resend a v2

> >          } else {
> >                  cmd->resp[0] = readl(base + MMCIRESPONSE0);
> >                  cmd->resp[1] = readl(base + MMCIRESPONSE1);
> > @@ -1532,9 +1536,9 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
> >   {
> >          struct mmci_host *host = dev_id;
> >          u32 status;
> > -       int ret = 0;
> >
> >          spin_lock(&host->lock);
> > +       host->irq_action = IRQ_HANDLED;
> >
> >          do {
> >                  status = readl(host->base + MMCISTATUS);
> > @@ -1574,12 +1578,41 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
> >                  if (host->variant->busy_detect_flag)
> >                          status &= ~host->variant->busy_detect_flag;
> >
> > -               ret = 1;
> >          } while (status);
> >
> >          spin_unlock(&host->lock);
> >
> > -       return IRQ_RETVAL(ret);
> > +       return host->irq_action;
> > +}
> > +
> > +/*
> > + * mmci_irq_threaded is call if the mmci host need to release state machines
> > + * before to terminate the request.
> > + * If datatimeout occurs on R1B request, the Data Path State Machine stays
> > + * in busy and is non-functional. Only a reset can to abort the DPSM.
> > + */
> > +static irqreturn_t mmci_irq_threaded(int irq, void *dev_id)
> > +{
> > +       struct mmci_host *host = dev_id;
> > +       unsigned long flags;
> > +
> > +       if (host->rst) {
> > +               reset_control_assert(host->rst);
> > +               udelay(2);
> > +               reset_control_deassert(host->rst);
> > +       }
> > +
> > +       spin_lock_irqsave(&host->lock, flags);
> > +       writel(host->clk_reg, host->base + MMCICLOCK);
> > +       writel(host->pwr_reg, host->base + MMCIPOWER);
> > +       writel(MCI_IRQENABLE | host->variant->start_err,
> > +              host->base + MMCIMASK0);
> > +
> > +       host->irq_action = IRQ_HANDLED;
> > +       mmci_request_end(host, host->mrq);
> > +       spin_unlock_irqrestore(&host->lock, flags);
> > +
> > +       return host->irq_action;
> >   }
> >
> >   static void mmci_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > @@ -2071,8 +2104,9 @@ static int mmci_probe(struct amba_device *dev,
> >                          goto clk_disable;
> >          }
> >
> > -       ret = devm_request_irq(&dev->dev, dev->irq[0], mmci_irq, IRQF_SHARED,
> > -                       DRIVER_NAME " (cmd)", host);
> > +       ret = devm_request_threaded_irq(&dev->dev, dev->irq[0], mmci_irq,
> > +                                       mmci_irq_threaded, IRQF_SHARED,
> > +                                       DRIVER_NAME " (cmd)", host);
> >          if (ret)
> >                  goto clk_disable;
> >
> > diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> > index 158e1231aa23..5e63c0596364 100644
> > --- a/drivers/mmc/host/mmci.h
> > +++ b/drivers/mmc/host/mmci.h
> > @@ -412,6 +412,7 @@ struct mmci_host {
> >
> >          struct timer_list       timer;
> >          unsigned int            oldstat;
> > +       u32                     irq_action;
> >
> >          /* pio stuff */
> >          struct sg_mapping_iter  sg_miter;
> > --
> > 2.17.1
>
> Otherwise this looks good, besides my other earlier comments, of course.
>
> Kind regards
> Uffe