mmc: sdhci: check interrupt flags in ISR again

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>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -2267,8 +2267,8 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
 {
 	irqreturn_t result;
 	struct sdhci_host *host = dev_id;
-	u32 intmask;
-	int cardint = 0;
+	u32 intmask, unexpected = 0;
+	int cardint = 0, max_loops = 16;
 
 	spin_lock(&host->lock);
 
@@ -2286,6 +2286,7 @@ 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);
 
@@ -2344,19 +2345,23 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
 	intmask &= ~SDHCI_INT_CARD_INT;
 
 	if (intmask) {
-		pr_err("%s: Unexpected interrupt 0x%08x.\n",
-			mmc_hostname(host->mmc), intmask);
-		sdhci_dumpregs(host);
-
+		unexpected |= intmask;
 		sdhci_writel(host, intmask, SDHCI_INT_STATUS);
 	}
 
 	result = IRQ_HANDLED;
 
-	mmiowb();
+	intmask = sdhci_readl(host, SDHCI_INT_STATUS);
+	if (intmask && --max_loops)
+		goto again;
 out:
 	spin_unlock(&host->lock);
 
+	if (unexpected) {
+		pr_err("%s: Unexpected interrupt 0x%08x.\n",
+			   mmc_hostname(host->mmc), unexpected);
+		sdhci_dumpregs(host);
+	}
 	/*
 	 * We have to delay this as it calls back into the driver.
 	 */