Misc display sync fixes #15259
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Misc display sync fixes #15259
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into get_display_synced_frame_end. Used in next commit.
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kasper93
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Nov 4, 2024
video/out/vo.c
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| @@ -489,11 +489,14 @@ static void update_vsync_timing_after_swap(struct vo *vo, | |||
| } | |||
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| in->num_successive_vsyncs++; | |||
| if (in->num_successive_vsyncs <= DELAY_VSYNC_SAMPLES) | |||
| if (in->num_successive_vsyncs <= DELAY_VSYNC_SAMPLES) { | |||
| in->base_vsync += in->vsync_interval; | |||
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I don't think it is correct to increment base_vsync here. It is updated in update_vsync_timing_after_swap and this function makes sure valid value is used. base_vsync is last valid point, incrementing with with interval will accumulate a lot of drift, making this value unreliable.
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I guess it makes more sense to set it to the actual vsync instead of incrementing by nominal vsync interval. Updated the patch
This is still used for caclulating a/v sync and delay remaining even for initial samples, so we should always update it with nominal vsync interval. And if we receive bogus values, also reset it to 0 along with prev_vsync.
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First two commits are entirely theoretical, it's more correct but it probably doesn't matter much because this code is only used to detect underruns and to wait for a frame to finish before applying new image_params.
Third commit fixes a real world problem with bad drivers that I encountered while testing various wip fifo-v1/commit-timing implementations. By not always updating base_vsync, we could potentially end up in a permanent underflow state and never recover from it even once the driver has stopped giving us bogus values.