[SCSI] usb-storage: add support for write cache quirk
Namjae Jeon [Sun, 8 Jul 2012 03:05:28 +0000 (23:05 -0400)]
Add support for write cache quirk on usb hdd. scsi driver will be set to wce
by detecting write cache quirk in quirk list when plugging usb hdd.

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>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

Documentation/kernel-parameters.txt
drivers/usb/storage/scsiglue.c
drivers/usb/storage/usb.c
include/linux/usb_usual.h

index a92c5eb..c68634e 100644 (file)
@@ -2932,6 +2932,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                                        initial READ(10) command);
                                o = CAPACITY_OK (accept the capacity
                                        reported by the device);
+                               p = WRITE_CACHE (the device cache is ON
+                                       by default);
                                r = IGNORE_RESIDUE (the device reports
                                        bogus residue values);
                                s = SINGLE_LUN (the device has only one
index 11418da..a3d5436 100644 (file)
@@ -236,6 +236,11 @@ static int slave_configure(struct scsi_device *sdev)
                                        US_FL_SCM_MULT_TARG)) &&
                                us->protocol == USB_PR_BULK)
                        us->use_last_sector_hacks = 1;
+
+               /* Check if write cache default on flag is set or not */
+               if (us->fflags & US_FL_WRITE_CACHE)
+                       sdev->wce_default_on = 1;
+
        } else {
 
                /* Non-disk-type devices don't need to blacklist any pages
index e23c30a..d012fe4 100644 (file)
@@ -473,7 +473,7 @@ static void adjust_quirks(struct us_data *us)
                        US_FL_CAPACITY_OK | US_FL_IGNORE_RESIDUE |
                        US_FL_SINGLE_LUN | US_FL_NO_WP_DETECT |
                        US_FL_NO_READ_DISC_INFO | US_FL_NO_READ_CAPACITY_16 |
-                       US_FL_INITIAL_READ10);
+                       US_FL_INITIAL_READ10 | US_FL_WRITE_CACHE);
 
        p = quirks;
        while (*p) {
@@ -529,6 +529,9 @@ static void adjust_quirks(struct us_data *us)
                case 'o':
                        f |= US_FL_CAPACITY_OK;
                        break;
+               case 'p':
+                       f |= US_FL_WRITE_CACHE;
+                       break;
                case 'r':
                        f |= US_FL_IGNORE_RESIDUE;
                        break;
index 17df360..e84e769 100644 (file)
@@ -64,7 +64,9 @@
        US_FLAG(NO_READ_CAPACITY_16,    0x00080000)             \
                /* cannot handle READ_CAPACITY_16 */            \
        US_FLAG(INITIAL_READ10, 0x00100000)                     \
-               /* Initial READ(10) (and others) must be retried */
+               /* Initial READ(10) (and others) must be retried */     \
+       US_FLAG(WRITE_CACHE,    0x00200000)                     \
+               /* Write Cache status is not available */
 
 #define US_FLAG(name, value)   US_FL_##name = value ,
 enum { US_DO_ALL_FLAGS };