[SCSI] scsi_transport_spi: fix domain validation failure from incorrect width setting

Domain Validation in the SPI transport class is failing on boxes with
damaged cables (and failing to the extent that the box hangs).  The
problem is that the first test it does is a cable integrity test for
wide transfers and if this fails, it turns the wide bit off.  The
problem is that the next set of tests it does turns wide back on
again, with the result that it runs through the entirety of DV with a
known bad setting and then hangs the system.

The attached patch fixes the problem by physically nailing the wide
setting to what it deduces it should be for the whole of Domain
Validation.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_transport_spi.c

@@ -787,6 +787,8 @@ spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
 	struct scsi_target *starget = sdev->sdev_target;
 	struct Scsi_Host *shost = sdev->host;
 	int len = sdev->inquiry_len;
+	int min_period = spi_min_period(starget);
+	int max_width = spi_max_width(starget);
 	/* first set us up for narrow async */
 	DV_SET(offset, 0);
 	DV_SET(width, 0);
@@ -798,9 +800,13 @@ spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
 		return;
 	}
 
+	if (!scsi_device_wide(sdev)) {
+		spi_max_width(starget) = 0;
+		max_width = 0;
+	}
+
 	/* test width */
-	if (i->f->set_width && spi_max_width(starget) &&
-	    scsi_device_wide(sdev)) {
+	if (i->f->set_width && max_width) {
 		i->f->set_width(starget, 1);
 
 		if (spi_dv_device_compare_inquiry(sdev, buffer,
@@ -809,6 +815,11 @@ spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
 		    != SPI_COMPARE_SUCCESS) {
 			starget_printk(KERN_ERR, starget, "Wide Transfers Fail\n");
 			i->f->set_width(starget, 0);
+			/* Make sure we don't force wide back on by asking
+			 * for a transfer period that requires it */
+			max_width = 0;
+			if (min_period < 10)
+				min_period = 10;
 		}
 	}
 
@@ -828,7 +839,8 @@ spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
 
 	/* now set up to the maximum */
 	DV_SET(offset, spi_max_offset(starget));
-	DV_SET(period, spi_min_period(starget));
+	DV_SET(period, min_period);
+
 	/* try QAS requests; this should be harmless to set if the
 	 * target supports it */
 	if (scsi_device_qas(sdev)) {
@@ -837,14 +849,14 @@ spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
 		DV_SET(qas, 0);
 	}
 
-	if (scsi_device_ius(sdev) && spi_min_period(starget) < 9) {
+	if (scsi_device_ius(sdev) && min_period < 9) {
 		/* This u320 (or u640). Set IU transfers */
 		DV_SET(iu, 1);
 		/* Then set the optional parameters */
 		DV_SET(rd_strm, 1);
 		DV_SET(wr_flow, 1);
 		DV_SET(rti, 1);
-		if (spi_min_period(starget) == 8)
+		if (min_period == 8)
 			DV_SET(pcomp_en, 1);
 	} else {
 		DV_SET(iu, 0);
@@ -862,6 +874,10 @@ spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
 	} else {
 		DV_SET(dt, 1);
 	}
+	/* set width last because it will pull all the other
+	 * parameters down to required values */
+	DV_SET(width, max_width);
+
 	/* Do the read only INQUIRY tests */
 	spi_dv_retrain(sdev, buffer, buffer + sdev->inquiry_len,
 		       spi_dv_device_compare_inquiry);