On 4/6/20 9:29 AM, Dmitry Osipenko wrote:
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06.04.2020 19:12, Sowjanya Komatineni пишет:
On 4/6/20 9:05 AM, Dmitry Osipenko wrote:
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06.04.2020 18:35, Sowjanya Komatineni пишет:
...
+ /* wait for syncpt counter to reach frame start event
threshold */
+ err = host1x_syncpt_wait(chan->frame_start_sp, thresh,
+ TEGRA_VI_SYNCPT_WAIT_TIMEOUT, &value);
+ if (err) {
+ dev_err(&chan->video.dev,
+ "frame start syncpt timeout: %d\n", err);
+ /* increment syncpoint counter for timedout events */
+ host1x_syncpt_incr(chan->frame_start_sp);
Why incrementing is done while hardware is still active?
The sync point's state needs to be completely reset after resetting
hardware. But I don't think that the current upstream host1x driver
supports doing that, it's one of the known-long-standing problems of
the
host1x driver.
At least the sp->max_val incrementing should be done based on the
actual
syncpoint value and this should be done after resetting hardware.
upstream host1x driver don't have API to reset or to equalize max value
with min/load value.
So to synchronize missed event, incrementing HW syncpt counter.
This should not impact as we increment this in case of missed events
only.
It's wrong to touch sync point while hardware is active and it's active
until being reset.
You should re-check the timeout after hw resetting and manually put the
syncpoint counter back into sync only if needed.
There is possibility of timeout to happen any time even during the
capture also and is not related to hw reset.
Manual synchronization is needed when timeout of any frame events happen
otherwise all subsequence frames will timeout due to mismatch in event
counters.
My point is that hardware is stopped only after being reset, until then
you should assume that sync point could be incremented by HW at any time.
And if this happens that HW increments sync point after the timeout,
then the sync point counter should become out-of-sync in yours case,
IIUC. Because host1x_syncpt_incr() doesn't update the cached counter.
We wait for enough time based on frame rate for syncpt increment to
happen and if it doesn't happen by then definitely its missed event and
we increment HW syncpoint for this timed event.
cached value gets updated during syncpt wait for subsequent event.
syncpt increment happens for all subsequent frame events during video
capture.
