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authorWolfgang Muees <wolfgang.mues@auerswald.de>2009-03-16 12:23:03 +0100
committerPierre Ossman <drzeus@drzeus.cx>2009-03-24 21:30:07 +0100
commitf079a8fc61e3dc35830f6abc58c21ae815ab4297 (patch)
tree20366f36bbe6e07d578e95ffa40bde583cb26706 /drivers
parente13bb3003a33df8f82cd027f8abfa5cd73f2eec0 (diff)
mmc_spi: adjust for delayed data token response
Some cards are not able to send the data token in time, but miss the time frame for some bits(!). So synchronize to the start of the token. Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de> Acked-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/mmc/host/mmc_spi.c27
1 files changed, 24 insertions, 3 deletions
diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
index 69e1442ff2e..72f8bde4877 100644
--- 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);