[SCSI] sd: don't fail if the device doesn't recognize SYNCHRONIZE CACHE

Evidently some wacky USB-ATA bridges don't recognize the SYNCHRONIZE
CACHE command, as shown in this email thread:

	http://marc.info/?t=138978356200002&r=1&w=2

The fact that we can't tell them to drain their caches shouldn't
prevent the system from going into suspend.  Therefore sd_sync_cache()
shouldn't return an error if the device replies with an Invalid
Command ASC.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Sven Neumann <s.neumann@raumfeld.com>
Tested-by: Daniel Mack <zonque@gmail.com>
CC: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 470954aba728..36d1a23f14be 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1463,8 +1463,8 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
                         sd_print_sense_hdr(sdkp, &sshdr);
                 /* we need to evaluate the error return  */
                 if (scsi_sense_valid(&sshdr) &&
-                        /* 0x3a is medium not present */
-                        sshdr.asc == 0x3a)
+                        (sshdr.asc == 0x3a ||   /* medium not present */
+                         sshdr.asc == 0x20))    /* invalid command */
                                 /* this is no error here */
                                 return 0;