usb: storage: add support for write cache quirk

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>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a92c5ebf373e2bf4bea68072b58fbc0471ad9c13..c68634edd4513cd61b3a84f69c31555472ec9452 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -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

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 11418da9bc0927492b820383ca433f309897e2fe..a3d54366afccde598a4ba5f3240909044f975266 100644 (file)
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -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

diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index e23c30ab66dae92724f5f22adbcb56c5f59ff87a..d012fe4329e7a36660d23f46195bdb86f511f21e 100644 (file)
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -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;

diff --git a/include/linux/usb_usual.h b/include/linux/usb_usual.h
index 17df3600bcef74bf674b9d13c9db5657e64cc558..e84e769aaddc39ec51515c0b1169727115c51ad9 100644 (file)
--- a/include/linux/usb_usual.h
+++ b/include/linux/usb_usual.h
@@ -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 };