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scsi: ufs: Fix broken task management command implementation

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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>
This commit is contained in:
Sujit Reddy Thumma
2014-05-26 10:59:12 +05:30
committed by Christoph Hellwig
parent bdbe5d2fe6
commit e293313262
2 changed files with 122 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/scsi/ufs/ufshcd.h
+6 -2
View File
@@ -174,7 +174,9 @@ struct ufs_dev_cmd {
* @irq: Irq number of the controller
* @active_uic_cmd: handle of active UIC command
* @uic_cmd_mutex: mutex for uic command
* @ufshcd_tm_wait_queue: wait queue for task management
* @tm_wq: wait queue for task management
* @tm_tag_wq: wait queue for free task management slots
* @tm_slots_in_use: bit map of task management request slots in use
* @pwr_done: completion for power mode change
* @tm_condition: condition variable for task management
* @ufshcd_state: UFSHCD states
@@ -217,8 +219,10 @@ struct ufs_hba {
struct uic_command *active_uic_cmd;
struct mutex uic_cmd_mutex;
wait_queue_head_t ufshcd_tm_wait_queue;
wait_queue_head_t tm_wq;
wait_queue_head_t tm_tag_wq;
unsigned long tm_condition;
unsigned long tm_slots_in_use;
struct completion *pwr_done;