[PATCH] Fix IDE bus reset and DMA disable when reading blank DVD-R

From Jon Burgess:

  There is a problems with blank DVD media using the ide-cd driver.

  When we attempt to read the blank disk, the drive responds to the read
  request by returning a "blank media" error.  The kernel doesn't have
  any special case handling for this sense value and retries the request
  a couple of times, then gives up and does a bus reset and disables DMA
  to the device.

  Which obviously doesn't help the situation.

  The sense key value of 8 isn't listed in ide-cd.h, but it is listed in
  scsi.h as a "BLANK_CHECK" error.

  This trivial patch treats this error condition as a reason to abort
  the request.  This behaviour is the same as what we do with a blank CD-R.

  It looks like the same fix might be desired for 2.4 as well, although
  is perhaps not so important since scsi-ide is normally used instead.

drivers/ide/ide-cd.c

@@ -799,6 +799,10 @@ static int cdrom_decode_status(ide_drive_t *drive, int good_stat, int *stat_ret)
 			 * sector...  If we got here the error is not correctable */
 			ide_dump_status (drive, "media error (bad sector)", stat);
 			do_end_request = 1;
+		} else if (sense_key == BLANK_CHECK) {
+			/* Disk appears blank ?? */
+			ide_dump_status (drive, "media error (blank)", stat);
+			do_end_request = 1;
 		} else if ((err & ~ABRT_ERR) != 0) {
 			/* Go to the default handler
 			   for other errors. */

drivers/ide/ide-cd.h

@@ -501,6 +501,7 @@ struct cdrom_info {
 #define ILLEGAL_REQUEST         0x05
 #define UNIT_ATTENTION          0x06
 #define DATA_PROTECT            0x07
+#define BLANK_CHECK             0x08
 #define ABORTED_COMMAND         0x0b
 #define MISCOMPARE              0x0e
 
@@ -578,7 +579,7 @@ const char * const sense_key_texts[16] = {
 	"Illegal request",
 	"Unit attention",
 	"Data protect",
-	"(reserved)",
+	"Blank check",
 	"(reserved)",
 	"(reserved)",
 	"Aborted command",