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    SubjectRe: [PATCH 2/3] mmc: sdhci: check interrupt flags in ISR again
    On 13/03/12 19:16, Alexander Stein wrote:
    > When using MSI it is possible that a new MSI is sent while an earlier
    > MSI is currently handled. In this case SDHCI_INT_STATUS only contains
    > SDHCI_INT_RESPONSE and the ISR would not be called again. But at the end
    > of the ISR SDHCI_INT_DATA_END is now also pending which would be ignored.
    >
    > Fix this by rereading the interrupt flags in the ISR until no interrupt
    > we care is pending.
    >
    > Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
    > ---
    > drivers/mmc/host/sdhci.c | 10 ++++++++++
    > 1 files changed, 10 insertions(+), 0 deletions(-)
    >
    > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
    > index 8d66706..654ab32 100644
    > --- a/drivers/mmc/host/sdhci.c
    > +++ b/drivers/mmc/host/sdhci.c
    > @@ -2268,6 +2268,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
    > irqreturn_t result;
    > struct sdhci_host *host = dev_id;
    > u32 intmask;
    > + u32 intmask_unhandled;
    > int cardint = 0;
    >
    > spin_lock(&host->lock);
    > @@ -2286,6 +2287,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
    > goto out;
    > }
    >
    > +again:
    > DBG("*** %s got interrupt: 0x%08x\n",
    > mmc_hostname(host->mmc), intmask);
    >
    > @@ -2336,6 +2338,14 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
    > sdhci_writel(host, SDHCI_INT_BUS_POWER, SDHCI_INT_STATUS);
    > }
    >
    > + intmask_unhandled = intmask;
    > +
    > + intmask = sdhci_readl(host, SDHCI_INT_STATUS);
    > +
    > + /* Do interrupt handling again if we got new flags */
    > + if (intmask & ~intmask_unhandled)
    > + goto again;
    > +
    > intmask &= ~SDHCI_INT_BUS_POWER;
    >
    > if (intmask & SDHCI_INT_CARD_INT)

    Why not just replace mmiowb() i.e.


    diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
    index 8d66706..da8a101 100644
    --- a/drivers/mmc/host/sdhci.c
    +++ b/drivers/mmc/host/sdhci.c
    @@ -2353,7 +2353,9 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)

    result = IRQ_HANDLED;

    - mmiowb();
    + intmask = sdhci_readl(host, SDHCI_INT_STATUS);
    + if (intmask)
    + goto again;
    out:
    spin_unlock(&host->lock);

    But maybe it would be safer limiting the number of loops i.e.


    diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
    index 8d66706..d88247d 100644
    --- a/drivers/mmc/host/sdhci.c
    +++ b/drivers/mmc/host/sdhci.c
    @@ -2268,7 +2268,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
    irqreturn_t result;
    struct sdhci_host *host = dev_id;
    u32 intmask;
    - int cardint = 0;
    + int cardint = 0, max_loops = 16;

    spin_lock(&host->lock);

    @@ -2353,7 +2353,9 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)

    result = IRQ_HANDLED;

    - mmiowb();
    + intmask = sdhci_readl(host, SDHCI_INT_STATUS);
    + if (intmask && --max_loops)
    + goto again;
    out:
    spin_unlock(&host->lock);



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