Veera Sundaram Sankaran 430a4283cb UPSTREAM: dma-fence: allow signaling drivers to set fence timestamp ...

Some drivers have hardware capability to get the precise HW timestamp
of certain events based on which the fences are triggered. The delta
between the event HW timestamp & current HW reference timestamp can
be used to calculate the timestamp in kernel's CLOCK_MONOTONIC time
domain. This allows it to set accurate timestamp factoring out any
software and IRQ latencies. Add a timestamp variant of fence signal
function, dma_fence_signal_timestamp to allow drivers to update the
precise timestamp for fences.

Changes in v2:
- Add a new fence signal variant instead of modifying fence struct

Changes in v3:
- Add timestamp domain information to commit-text and
dma_fence_signal_timestamp documentation

Bug: 173434777
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>
Signed-off-by: Narendra Muppalla <NarendraM@codeaurora.org>
Reviewed-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
 [sumits: minor parenthesis alignment]
Link: https://patchwork.freedesktop.org/patch/msgid/1610757107-11892-1-git-send-email-veeras@codeaurora.org
(cherry picked from commit 5a164ac4dbd21b82bcdc03186d40e455ff467fdc)
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Change-Id: I994fb91264aac1f5c141415647df3467819ff1f3

2021-04-07 14:17:51 +00:00

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