tree 6faf0175dc373189f8d2c7524a28d03fd32d9324
parent bde44bb665d049468b6a1a2fa7d666434de4f83f
author subhashj@codeaurora.org <subhashj@codeaurora.org> 1479947512 -0800
committer Martin K. Petersen <martin.petersen@oracle.com> 1480439216 -0500

scsi: ufs: increase the scsi query response timeout

It is found thats UFS device may take longer than 30ms to respond to
query requests and in this case we might run into following scenario:

1. UFS host SW sends a query request to UFS device to read an attribute
   value. SW uses tag #31 for this purpose.
2. UFS host SW waits for 30ms to get the query response (and doorbell
   to be cleared by UFS host HW).
3. UFS device doesn't respond back within 30ms hence UFS host SW times
   out waiting for the query response.
4. UFS host SW clears the tag#31 from UTRLCLR register.
5. UFS host SW waits until UFS host HW to clear tag#31 from the doorbell
   register.
6. UFS host SW retries the same query request on same tag#31 (sends a query
   request to device to read an attribute value).
7. UFS host HW gets the query response from the device but this was
   intended as a query response for the 1st query request sent (step-1).
8. Now UFS device sends another query response to host (for query request
   sent @step-6).

Now there are 2 issues that could happen with above scenario:
1. UFS device should have actually responded back with only one query
   response but it is found that device may respond back with 2 query
   responses.
2. If UFS device responds back with 2 resposes on same tag, host HW/SW
   behaviour isn't predictable.

To avoid running into above scenario, we would basically allow device
to take longer (upto 1.5 seconds) for query response.

Reviewed-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>