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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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