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>

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a92c5ebf373e..c68634edd451 100644
--- 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