x1250 horizontal tearing problems

[Roland Scheidegger]

Michel Dänzer wrote:
> On Wed, 2008-04-30 at 14:39 -0400, Alex Deucher wrote: 
>> On Wed, Apr 30, 2008 at 3:06 AM, Michel Dänzer
>> <michel at tungstengraphics.com> wrote:
>>> On Tue, 2008-04-29 at 16:52 -0400, Alex Deucher wrote:
>>>  > On Tue, Apr 29, 2008 at 4:34 PM, Alex Rades <alerades at gmail.com> wrote:
>>>  > > Hi,
>>>  > > when playing videos (either in xv or plain x11) on my x1250, I always see
>>>  > > horizontal (not diagonal, which are now fixed) tearing problems. They seem
>>>  > > related to vertical sync problems. Do you have suggestions?
>>>  >
>>>  > We need sync to vblank support for textured video to properly deal
>>>  > with that.  this untested hack may help, but it's not optimal:
>>>  > http://www.botchco.com/alex/xorg/texvid_wait_vsync.diff
>>>
>>>  Good to see this getting tackled. Here's what I think is missing:
>>>
>>>       * Set up the CRTC*_GUI_TRIG_VLINE register such that it waits for
>>>         scanout to be outside of the destination vertical range.
>> yeah, makes sense.
>>
>>>       * Only wait if the window isn't redirected (backing pixmap is the
>>>         screen pixmap)
>> yeah, as you said, any rendering to the front buffer should wait for
>> vblank.  
> 
> Technically not for vblank, but for scanout to be outside of the
> affected vertical screen range.
> 
>> I may play around with it a bit if I have time, but unfortunately, I
>> seem to be unable to notice tearing generally.  Do you have any good
>> tips or content that would make it easier to notice?
> 
> Generally, I find it most noticeable with horizontal animation or with
> large solid areas that continuously change colour.
> 
>> The other issue is that the current IB scheme doesn't really lend
>> itself to this.  Ideally we'd queue up everything and then pre-pend a
>> wait_until vblank when we submit the IB.
> 
> I don't think one wait per IB is sufficient anyway, as any given IB will
> likely have both on- and offscreen operations. It could be tricky to
> find a good granularity for the waits.
> 
>> Additionally, we have the issue of multiple crtcs for regular
>> rendering as well. In that case, we really need shatter.
> 
> Right, or again pick the CRTC with larger visibility and/or let the user
> choose somehow.

Since nowadays everybody just uses 60Hz for almost all displays
(LCD...), wouldn't it be possible to sync them? Looks to me like the
avivo-based chips could do that (with the D1CRTC_TRIGA_CNTL and friends)
or is my quick look wrong?

Roland