[PATCH] PATCH: (as255) Handle Unit Attention during INQUIRY better

Some buggy USB storage devices can return Unit Attention status for
INQUIRY commands.  The current code in scsi_scan.c checks for ASC = 0x28 =
Not ready to ready transition, but these devices can also return ASC =
0x29 = Power-on or reset occurred.  In addition, the code doesn't retry
the INQUIRY when these codes are received.

drivers/scsi/scsi_scan.c

@@ -330,6 +330,7 @@ static void scsi_probe_lun(struct scsi_request *sreq, char *inq_result,
 	struct scsi_device *sdev = sreq->sr_device;	/* a bit ugly */
 	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 	int possible_inq_resp_len;
+	int count = 0;
 
 	*bflags = 0;
  repeat_inquiry:
@@ -350,19 +351,24 @@ static void scsi_probe_lun(struct scsi_request *sreq, char *inq_result,
 	SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO "scsi scan: 1st INQUIRY %s with"
 			" code 0x%x\n", sreq->sr_result ?
 			"failed" : "successful", sreq->sr_result));
+	++count;
 
 	if (sreq->sr_result) {
 		if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) != 0 &&
 		    (sreq->sr_sense_buffer[2] & 0xf) == UNIT_ATTENTION &&
-		    sreq->sr_sense_buffer[12] == 0x28 &&
+		    (sreq->sr_sense_buffer[12] == 0x28 ||
+		     sreq->sr_sense_buffer[12] == 0x29) &&
 		    sreq->sr_sense_buffer[13] == 0) {
-			/* not-ready to ready transition - good */
+			/* not-ready to ready transition or power-on - good */
 			/* dpg: bogus? INQUIRY never returns UNIT_ATTENTION */
-		} else
-			/*
-			 * assume no peripheral if any other sort of error
-			 */
-			return;
+			/* Supposedly, but many buggy devices do so anyway */
+			if (count < 3)
+				goto repeat_inquiry;
+		}
+		/*
+		 * assume no peripheral if any other sort of error
+		 */
+		return;
 	}
 
 	/*