Alan,
This is in response to your post:
http://marc.theaimsgroup.com/?l=linux-scsi&m=112982432526039&w=2
in a thread titled:
[PATCH] Improve code for detecting errors near the end of a CD
This patch should allow for the flexibility to handle
MMC devices that don't set the valid bit when putting
a lba in the information field.
The patch is against lk 2.6.14-rc5 .
Changelog:
- make scsi_get_sense_info_fld() yield the sense
data information field, or 0 if it is not available
- the return value is the state of the valid bit in
the sense data
Signed-off-by: Douglas Gilbert <dougg@xxxxxxxxxx>
Doug Gilbert
--- linux/drivers/scsi/scsi_error.c 2005-10-22 15:45:31.000000000 +1000
+++ linux/drivers/scsi/scsi_error.c2614rc5inf 2005-10-26 10:53:59.000000000 +1000
@@ -1929,11 +1929,17 @@
*
* @sense_buffer: byte array of sense data
* @sb_len: number of valid bytes in sense_buffer
- * @info_out: pointer to 64 integer where 8 or 4 byte information
- * field will be placed if found.
+ * @info_out: pointer to 64 bit integer where 8 or 4 byte
+ * information field will be placed if found,
+ * else 0 is written via pointer
+ *
+ * Notes:
+ * Due to fuzziness in the MMC standard, a MMC device may (and some
+ * do) set the information field without also setting the valid bit.
*
* Return value:
- * 1 if information field found, 0 if not found.
+ * 1 if valid bit is set, 0 if it is clear. Even when the return value
+ * is 0, the information field may be fetched.
**/
int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
u64 * info_out)
@@ -1942,18 +1948,16 @@
const u8 * ucp;
u64 ull;
+ *info_out = 0;
if (sb_len < 7)
return 0;
switch (sense_buffer[0] & 0x7f) {
case 0x70:
case 0x71:
- if (sense_buffer[0] & 0x80) {
- *info_out = (sense_buffer[3] << 24) +
- (sense_buffer[4] << 16) +
- (sense_buffer[5] << 8) + sense_buffer[6];
- return 1;
- } else
- return 0;
+ *info_out = (sense_buffer[3] << 24) +
+ (sense_buffer[4] << 16) +
+ (sense_buffer[5] << 8) + sense_buffer[6];
+ return (sense_buffer[0] & 0x80) ? 1 : 0;
case 0x72:
case 0x73:
ucp = scsi_sense_desc_find(sense_buffer, sb_len,
@@ -1966,7 +1970,7 @@
ull |= ucp[4 + j];
}
*info_out = ull;
- return 1;
+ return 1; /* valid bit defined to be 1 */
} else
return 0;
default:
