sdhci: handle dma boundary interrupts

When the device hits certain memory boundaries, it signals an
interrupt and expects to be serviced. We don't need the feature
but we need to make sure the device doesn't stall.

Signed-off-by: Pierre Ossman <[e-mail]>

drivers/mmc/host/sdhci.c

···
 		if (intmask & (SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL))
 			sdhci_transfer_pio(host);
 
+		/*
+		 * We currently don't do anything fancy with DMA
+		 * boundaries, but as we can't disable the feature
+		 * we need to at least restart the transfer.
+		 */
+		if (intmask & SDHCI_INT_DMA_END)
+			writel(readl(host->ioaddr + SDHCI_DMA_ADDRESS),
+				host->ioaddr + SDHCI_DMA_ADDRESS);
+
 		if (intmask & SDHCI_INT_DATA_END)
 			sdhci_finish_data(host);
 	}