[PATCH v3 2/4] usb: storage: add support for write cache quirk on usb hdd

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>

drivers/usb/storage/scsiglue.c | 5 +++++
drivers/usb/storage/usb.c | 5 ++++-
include/linux/usb_usual.h | 4 +++-
3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index a324a5d..fe42547 100644
a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -230,6 +230,11 @@ 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 e23c30a..d012fe4 100644
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 17df360..96fc152 100644
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 };
1.7.9.5

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