Comment 27 for bug 1308515

(In reply to comment #13)
> The fix in your case should be fairly trivial, remove the
> sna_crtc->transform = true and remember to unoffset the CRTC. However,
> handling the transformed slaved CRTC was broken.
>
>
> commit a45b2ea11c15f35c36330ff27cb45854a29c2e2c
> Author: Chris Wilson <email address hidden>
> Date: Thu Jul 17 14:40:51 2014 +0100
>
> sna: Handle rotated slaved scanouts
>
> As per the usual handling of rotated scanouts with unsupported
> rotations, we stage the drawing onto a backbuffer then rotate onto the
> crtc later. The difference here is that we must read the contents from
> the master pixmap rather than our own screen pixmap.
>
> Spotted was looking at slaved scanouts mistakenly setting the CRTC
> transformed flag.
>
> Reported-by: Tomas Pruzina <email address hidden>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=81383
> Signed-off-by: Chris Wilson <email address hidden>

Thanks, I'll test it for a bit and report back if anything is unstable.