[SCSI] set to WCE if usb cache quirk is present.

Make use of USB quirk method to identify such HDD while reading
the cache status in sd_probe(). If cache quirk is present for
the HDD, lets assume that cache is enabled and make WCE bit
equal to 1.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 6e26db11250a..4df73e52a4f9 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2261,8 +2261,13 @@ bad_sense:
                 sd_printk(KERN_ERR, sdkp, "Asking for cache data failed\n");
 
 defaults:
-        sd_printk(KERN_ERR, sdkp, "Assuming drive cache: write through\n");
-        sdkp->WCE = 0;
+        if (sdp->wce_default_on) {
+                sd_printk(KERN_NOTICE, sdkp, "Assuming drive cache: write back\n");
+                sdkp->WCE = 1;
+        } else {
+                sd_printk(KERN_ERR, sdkp, "Assuming drive cache: write through\n");
+                sdkp->WCE = 0;
+        }
         sdkp->RCD = 0;
         sdkp->DPOFUA = 0;
 }