[MMC] sdhci: Avoid sdhci DMA boundaries

The sdhci controllers will issue an interrupt when a configurable number of
bytes have been transfered using DMA. The purpose is to handle multiple,
scattered memory pages.

Unfortunately, it requires that all transfers are completely aligned to
memory pages, which we cannot guarantee. So we just disable the function.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 8e480140cd289d1bb9550bae7a6682cb89ed77d2..95fe0fdac4849a43f3f6d5345e92a7f61731fae8 100644 (file)
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -326,6 +326,9 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
        DBG("tsac %d ms nsac %d clk\n",
                data->timeout_ns / 1000000, data->timeout_clks);
 
+       /* Sanity checks */
+       BUG_ON(data->blksz * data->blocks > 524288);
+
        /* timeout in us */
        target_timeout = data->timeout_ns / 1000 +
                data->timeout_clks / host->clock;
@@ -375,7 +378,9 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
                host->remain = host->cur_sg->length;
        }
 
-       writew(data->blksz, host->ioaddr + SDHCI_BLOCK_SIZE);
+       /* We do not handle DMA boundaries, so set it to max (512 KiB) */
+       writew(SDHCI_MAKE_BLKSZ(7, data->blksz),
+               host->ioaddr + SDHCI_BLOCK_SIZE);
        writew(data->blocks, host->ioaddr + SDHCI_BLOCK_COUNT);
 }
 
@@ -1188,10 +1193,10 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot)
        mmc->max_phys_segs = 16;
 
        /*
-        * Maximum number of sectors in one transfer. Limited by sector
-        * count register.
+        * Maximum number of sectors in one transfer. Limited by DMA boundary
+        * size (512KiB), which means (512 KiB/512=) 1024 entries.
         */
-       mmc->max_sectors = 0x3FFF;
+       mmc->max_sectors = 1024;
 
        /*
         * Maximum segment size. Could be one segment with the maximum number

diff --git a/drivers/mmc/sdhci.h b/drivers/mmc/sdhci.h
index f8df28f8d6dd0c38558567db58b7cc75d9120e5d..8ed2a8973db6ff6fb4cb4f90f2508fce06e02448 100644 (file)
--- a/drivers/mmc/sdhci.h
+++ b/drivers/mmc/sdhci.h
@@ -23,6 +23,7 @@
 #define SDHCI_DMA_ADDRESS      0x00
 
 #define SDHCI_BLOCK_SIZE       0x04
+#define  SDHCI_MAKE_BLKSZ(dma, blksz) (((dma & 0x7) << 12) | (blksz & 0xFFF))
 
 #define SDHCI_BLOCK_COUNT      0x06