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[SCSI] 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>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Namjae Jeon 2012-07-07 23:05:28 -04:00 committed by James Bottomley
parent b81478d82e
commit eaa05dfcdb
4 changed files with 14 additions and 2 deletions
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2
Documentation/kernel-parameters.txt
View 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

5
drivers/usb/storage/scsiglue.c
View 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

5
drivers/usb/storage/usb.c
View 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;

4
include/linux/usb_usual.h
View 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 };