lkml.org 
[lkml]   [2009]   [May]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mmc_spi: use EILSEQ for possible transmission errors
Date
From: Wolfgang Muees <wolfgang.mues@auerswald.de>

o This patch changes the reported error code for the responses
to a command from EINVAL/EIO to EILSEQ, as EINVAL is reserved
for non-recoverable host errors, and the responses from
the SD/MMC card may be because of recoverable transmission
errors in the command or in the response. Response codes
are NOT protected by a checksum, so don't trust them.

Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>

---
diff -uprN 2_6_29_rc7_patch_wearout_speedup/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch_EILSEQ/drivers/mmc/host/mmc_spi.c
--- 2_6_29_rc7_patch_wearout_speedup/drivers/mmc/host/mmc_spi.c 2009-04-08 11:11:20.000000000 +0200
+++ 2_6_29_rc7_patch_EILSEQ/drivers/mmc/host/mmc_spi.c 2009-05-14 12:49:42.000000000 +0200
@@ -334,17 +334,18 @@ checkstatus:
cmd->error = 0;

/* Status byte: the entire seven-bit R1 response. */
- if (cmd->resp[0] != 0) {
- if ((R1_SPI_PARAMETER | R1_SPI_ADDRESS
- | R1_SPI_ILLEGAL_COMMAND)
- & cmd->resp[0])
- value = -EINVAL;
- else if (R1_SPI_COM_CRC & cmd->resp[0])
- value = -EILSEQ;
- else if ((R1_SPI_ERASE_SEQ | R1_SPI_ERASE_RESET)
- & cmd->resp[0])
- value = -EIO;
- /* else R1_SPI_IDLE, "it's resetting" */
+ /*
+ * Note that we have a problem here: as the response is NOT protected
+ * by a CRC or checksum, a transmission error in the response will
+ * be interpreted as an error code. So we map all error codes to
+ * EILSEQ here, to allow for the upper layer to retry the command.
+ * If one of these error codes is a non-recoverable error, retries
+ * will do no harm.
+ */
+
+ /* Allow only 0 and R1_SPI_IDLE here */
+ if (cmd->resp[0] & ~R1_SPI_IDLE) {
+ value = -EILSEQ;
}

switch (mmc_spi_resp_type(cmd)) {
---
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
 
--------------------------------------------------------------
Auerswald GmbH & Co. KG, Vor den Grashöfen 1, 38162 Cremlingen
Registriert beim AG Braunschweig HRA 13289
p.h.G Auerswald Geschäftsführungsges. mbH
Registriert beim AG Braunschweig HRB 7463
Geschäftsführer: Dipl-Ing. Gerhard Auerswald
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2009-05-14 13:27    [from the cache]
©2003-2011 Jasper Spaans