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Subject[PATCH 3/7] mmc_spi: adjust for delayed data token response
Date
From: Wolfgang Muees <wolfgang.mues@auerswald.de>

o 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>

---
This is one of a line of patches to enhance the usability of
the mmc spi host port driver from "don't work with most SD cards"
to "work with nearly all SD cards" (including those ugly cards
with non-byte-aligned responses).

diff -uprN 2_6_29_rc7_patch2_wait_16bytes_response/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch3_delayed_data_response/drivers/mmc/host/mmc_spi.c
--- 2_6_29_rc7_patch2_wait_16bytes_response/drivers/mmc/host/mmc_spi.c 2009-03-11 13:00:06.000000000 +0100
+++ 2_6_29_rc7_patch3_delayed_data_response/drivers/mmc/host/mmc_spi.c 2009-03-11 13:42:48.000000000 +0100
@@ -612,6 +612,7 @@ mmc_spi_writeblock(struct mmc_spi_host *
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 +640,23 @@ mmc_spi_writeblock(struct mmc_spi_host *
* 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.
- */
- switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) {
+ *
+ * In practice, there are (even modern SDHC-)Cards which need
+ * some bits to send the response, so we have to cope with this
+ * situation and check the response bit-by-bit. Arggh!!!
+ */
+ pattern = scratch->status[0] << 24;
+ pattern |= scratch->status[1] << 16;
+ pattern |= scratch->status[2] << 8;
+ pattern |= scratch->status[3];
+
+ /* 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 +687,8 @@ mmc_spi_writeblock(struct mmc_spi_host *
/* 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++) {
+ if (scratch->status[i] & 0x01)
return 0;
}
return mmc_spi_wait_unbusy(host, timeout);
---
regards
i. A. Wolfgang Mües
--
Auerswald GmbH & Co. KG
Hardware Development
Telefon: +49 (0)5306 9219 0
Telefax: +49 (0)5306 9219 94
E-Mail: Wolfgang.Mues@Auerswald.de
Web: http://www.auerswald.de
 
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