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Commit 459abfee authored by Subhash Jadavani's avatar Subhash Jadavani
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scsi: ufs: increase the scsi query response timeout



It is found thats UFS device may take longer than 100ms 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 100ms to get the query response (and doorbell
   to be cleared by UFS host HW).
3. UFS device doesn't respond back within 100ms 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.

CRs-Fixed: 966573
Change-Id: I9885cac614eff011b617064edcd31d0e8daddd45
Signed-off-by: default avatarSubhash Jadavani <subhashj@codeaurora.org>
parent bf1f2607
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