[Intel-gfx] BUG: i830 flickering for horizontal panning

[Daniel Vetter]

On Sat, Aug 31, 2013 at 05:40:09PM +0200, Thomas Richter wrote:
> Dear intel-gfx developers,
> 
> panning on i830 based graphics seem to be working only half-ways.
> Vertical panning works fine, but horizontal panning flickers at
> about 60Hz frequency at specific pixel positions. The problem
> persists throughout kernel 3.10.9, and potentially later.
> 
> How to reproduce: Enable panning, e.g. by
> 
> xrandr --fb 2048x1536
> xrandr --output DVI1 --panning 2048x1536
> 
> then scroll with the mouse slowly to the right.
> 
> The affected hardware is *at least* this one:
> 
> 00:02.0 VGA compatible controller: Intel Corporation 82830M/MG
> Integrated Graphics Controller (rev 04)
> 
> as it is found in the Fujitsu-Siemens S2475 lifebook. The IBM
> Thinkpad R31 is also affected, it also contains a 830GM chipset
> graphics, but a different DVO.
> 
> There is no specific output when flickering. The screen contents
> seems to be flickering between a dark frame and a frame that is half
> the way shifted correctly (left) and half the way a copy of the
> leftmost pixels of the screen on the right hand side.
> 
> The kernel uses the i915 driver for this hardware.
> 
> I currently don't see where precisely panning in the i915 sources is
> handled, thus I cannot really say what is necessary to support this
> correctly.

Is this a regression?

For your other bug reports we know that the modesetting support for i830M
chipsets is a bit in a sorry state of affairs, search for 830 at
bugs.freedesktop.org. Unfortunately time to really dig into this issues is
hard to come by :(
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch