scsi: ufs: Fix broken task management command implementation
authorSujit Reddy Thumma <sthumma@codeaurora.org>
Mon, 26 May 2014 05:29:12 +0000 (10:59 +0530)
committerChristoph Hellwig <hch@lst.de>
Wed, 28 May 2014 10:25:13 +0000 (12:25 +0200)
commite293313262d3c780632f7888878c982fa0a9bf7e
tree48b9f96f64240af775f982e2330764319f38af14
parentbdbe5d2fe67031bf51777afbfa91585efcf9dbf5
scsi: ufs: Fix broken task management command implementation

Currently, sending Task Management (TM) command to the card might
be broken in some scenarios as listed below:

Problem: If there are more than 8 TM commands the implementation
         returns error to the caller.
Fix:     Wait for one of the slots to be emptied and send the command.

Problem: Sometimes it is necessary for the caller to know the TM service
         response code to determine the task status.
Fix:     Propogate the service response to the caller.

Problem: If the TM command times out no proper error recovery is
         implemented.
Fix:     Clear the command in the controller door-bell register, so that
         further commands for the same slot don't fail.

Problem: While preparing the TM command descriptor, the task tag used
         should be unique across SCSI/NOP/QUERY/TM commands and not the
 task tag of the command which the TM command is trying to manage.
Fix:     Use a unique task tag instead of task tag of SCSI command.

Problem: Since the TM command involves H/W communication, abruptly ending
         the request on kill interrupt signal might cause h/w malfunction.
Fix:     Wait for hardware completion interrupt with TASK_UNINTERRUPTIBLE
         set.

Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Reviewed-by: Yaniv Gardi <ygardi@codeaurora.org>
Tested-by: Dolev Raviv <draviv@codeaurora.org>
Acked-by: Vinayak Holikatti <vinholikatti@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
drivers/scsi/ufs/ufshcd.c
drivers/scsi/ufs/ufshcd.h