x1250 horizontal tearing problems

[Alex Deucher]

On Thu, May 1, 2008 at 6:49 PM, Roland Scheidegger
<sroland at tungstengraphics.com> wrote:
>
> 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?

Probably.  if the mode was the same you could even use the same PLL for both.

Alex