linux-kernel - [PATCH] mmc_spi: don't use EINVAL for possible transmission errors

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Date:	Tue, 26 May 2009 08:56:19 +0100
From:	Wolfgang Mües <wolfgang.mues@...rswald.de>
To:	Pierre Ossman <drzeus@...eus.cx>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Matt Fleming" <matt@...sole-pimps.org>,
	"David Brownell" <dbrownell@...rs.sourceforge.net>,
	"Mike Frysinger" <vapier.adi@...il.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mmc_spi: don't use EINVAL for possible transmission errors

From: Wolfgang Muees <wolfgang.mues@...rswald.de>

o This patch changes the reported error code for the responses
  to a command from EINVAL to EFAULT/ENOSYS, 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
  in SPI mode are NOT protected by a checksum, so don't trust them.

This is a revised, minimal-invasive patch version. As Pierre Ossman
pointed out, EINVAL should only be used for non-recoverable errors
(and is used so in the whole rest of the mmc framework).

I have checked every instance of EINVAL in the mmc framework - no 
changes were needed here. 

This patch is neccessary for doing a sensible retry managment in the 
mmmc block layer (patch will follow).

Signed-off-by: Wolfgang Muees <wolfgang.mues@...rswald.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	2009-05-26 09:37:28.000000000 +0200
@@ -335,15 +335,16 @@ checkstatus:

 	/* Status byte: the entire seven-bit R1 response.  */
 	if (cmd->resp[0] != 0) {
-		if ((R1_SPI_PARAMETER | R1_SPI_ADDRESS
-				      | R1_SPI_ILLEGAL_COMMAND)
+		if ((R1_SPI_PARAMETER | R1_SPI_ADDRESS)
 				& cmd->resp[0])
-			value = -EINVAL;
+			value = -EFAULT; /* Bad address */
+		else if (R1_SPI_ILLEGAL_COMMAND & cmd->resp[0])
+			value = -ENOSYS; /* Function not implemented */
 		else if (R1_SPI_COM_CRC & cmd->resp[0])
-			value = -EILSEQ;
+			value = -EILSEQ; /* Illegal byte sequence */
 		else if ((R1_SPI_ERASE_SEQ | R1_SPI_ERASE_RESET)
 				& cmd->resp[0])
-			value = -EIO;
+			value = -EIO;    /* I/O error */
 		/* else R1_SPI_IDLE, "it's resetting" */
 	}

---
regards

i. A. Wolfgang Mües
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