drm/i915: enable low power render writes on GEN3 hardware.
A lot of 945GMs have had stability issues for a long time, this manifested as X hangs, blitter engine hangs, and lots of crashes.
one such report is at:
along with numerous distro bugzillas.
This only took a week of digging and hair ripping to figure out.
Tracked down and tested on a 945GM Lenovo T60,
repeatedly would cause the GPU to wedge within 4 or 5 tries, with random busy bits set.
After this patch no hangs were observed.
Signed-off-by: Dave Airlie <email@example.com>