mmc_spi: adjust for delayed data token response

[linux-2.6-omap-h63xx.git] / drivers / mmc / host / mmc_spi.c

diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
index 69e1442ff2e260b9bcd7795191df2297f3a8cb58..72f8bde4877a790f8d65f95450aae1723e521c84 100644 (file)
--- a/drivers/mmc/host/mmc_spi.c
+++ b/drivers/mmc/host/mmc_spi.c
@@ -612,6 +612,7 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,
        struct spi_device       *spi = host->spi;
        int                     status, i;
        struct scratch          *scratch = host->data;
+       u32                     pattern;
 
        if (host->mmc->use_spi_crc)
                scratch->crc_val = cpu_to_be16(
@@ -639,8 +640,27 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,
         * doesn't necessarily tell whether the write operation succeeded;
         * it just says if the transmission was ok and whether *earlier*
         * writes succeeded; see the standard.
+        *
+        * In practice, there are (even modern SDHC-)cards which are late
+        * in sending the response, and miss the time frame by a few bits,
+        * so we have to cope with this situation and check the response
+        * bit-by-bit. Arggh!!!
         */
-       switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) {
+       pattern  = scratch->status[0] << 24;
+       pattern |= scratch->status[1] << 16;
+       pattern |= scratch->status[2] << 8;
+       pattern |= scratch->status[3];
+
+       /* First 3 bit of pattern are undefined */
+       pattern |= 0xE0000000;
+
+       /* left-adjust to leading 0 bit */
+       while (pattern & 0x80000000)
+               pattern <<= 1;
+       /* right-adjust for pattern matching. Code is in bit 4..0 now. */
+       pattern >>= 27;
+
+       switch (pattern) {
        case SPI_RESPONSE_ACCEPTED:
                status = 0;
                break;
@@ -671,8 +691,9 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,
        /* Return when not busy.  If we didn't collect that status yet,
         * we'll need some more I/O.
         */
-       for (i = 1; i < sizeof(scratch->status); i++) {
-               if (scratch->status[i] != 0)
+       for (i = 4; i < sizeof(scratch->status); i++) {
+               /* card is non-busy if the most recent bit is 1 */
+               if (scratch->status[i] & 0x01)
                        return 0;
        }
        return mmc_spi_wait_unbusy(host, timeout);