[Mesa-dev] [PATCH] vl/dri3: remove the wait before getting back buffer

[Liu, Leo]

On 2019-03-21 4:15 a.m., Ernst Sjöstrand wrote:
> What's the expected change in behavior?

The change will make vl_dri3_screen_texture_from_drawable() call not to 
hold the pipeline. Because of the multiple of back buffers,  we can get 
the texture of the ongoing presented back buffer, and no need to wait 
the last presenting back buffer.

> Does it fix any bugs?

Yeah. With some of relatively slower hardware to play 4k at 60fps, the 
presentation will miss the targeted time, and make the duration of the 
playback longer than the actual. esp. like VDPAU with scheduled 
presentation.


Thanks,

Leo


>
> Regards
> //Ernst
>
> Den ons 20 mars 2019 kl 16:42 skrev Liu, Leo <Leo.Liu at amd.com>:
>> The wait here is unnecessary since we got a pool of back buffers,
>> and the wait for swap buffer will happen before the present pixmap,
>> at the same time the previous back buffer will be put back to pool
>> for reuse after the check for PresentIdleNotify event
>>
>> Signed-off-by: Leo Liu <leo.liu at amd.com>
>> ---
>>   src/gallium/auxiliary/vl/vl_winsys_dri3.c | 18 +++---------------
>>   1 file changed, 3 insertions(+), 15 deletions(-)
>>
>> diff --git a/src/gallium/auxiliary/vl/vl_winsys_dri3.c b/src/gallium/auxiliary/vl/vl_winsys_dri3.c
>> index 152d28e59fc..1558d832555 100644
>> --- a/src/gallium/auxiliary/vl/vl_winsys_dri3.c
>> +++ b/src/gallium/auxiliary/vl/vl_winsys_dri3.c
>> @@ -88,7 +88,6 @@ struct vl_dri3_screen
>>      uint64_t send_sbc, recv_sbc;
>>      int64_t last_ust, ns_frame, last_msc, next_msc;
>>
>> -   bool flushed;
>>      bool is_different_gpu;
>>   };
>>
>> @@ -570,11 +569,9 @@ vl_dri3_flush_frontbuffer(struct pipe_screen *screen,
>>      if (!back)
>>          return;
>>
>> -   if (scrn->flushed) {
>> -      while (scrn->special_event && scrn->recv_sbc < scrn->send_sbc)
>> -         if (!dri3_wait_present_events(scrn))
>> -            return;
>> -   }
>> +   while (scrn->special_event && scrn->recv_sbc < scrn->send_sbc)
>> +      if (!dri3_wait_present_events(scrn))
>> +         return;
>>
>>      rectangle.x = 0;
>>      rectangle.y = 0;
>> @@ -610,8 +607,6 @@ vl_dri3_flush_frontbuffer(struct pipe_screen *screen,
>>
>>      xcb_flush(scrn->conn);
>>
>> -   scrn->flushed = true;
>> -
>>      return;
>>   }
>>
>> @@ -626,13 +621,6 @@ vl_dri3_screen_texture_from_drawable(struct vl_screen *vscreen, void *drawable)
>>      if (!dri3_set_drawable(scrn, (Drawable)drawable))
>>         return NULL;
>>
>> -   if (scrn->flushed) {
>> -      while (scrn->special_event && scrn->recv_sbc < scrn->send_sbc)
>> -         if (!dri3_wait_present_events(scrn))
>> -            return NULL;
>> -   }
>> -   scrn->flushed = false;
>> -
>>      buffer = (scrn->is_pixmap) ?
>>               dri3_get_front_buffer(scrn) :
>>               dri3_get_back_buffer(scrn);
>> --
>> 2.17.1
>>
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