| Date | Fri, 30 Jul 2010 10:30:15 -0700 | From | Greg KH <> | Subject | [050/140] drm/i915: enable low power render writes on GEN3 hardware. |
| |
2.6.33-stable review patch. If anyone has any objections, please let us know.
------------------
From: Dave Airlie <airlied@redhat.com>
commit 944001201ca0196bcdb088129e5866a9f379d08c upstream.
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: https://bugs.freedesktop.org/show_bug.cgi?id=20560
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, previously running x11perf -copypixwin500 or x11perf -copywinpix500 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 <airlied@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/gpu/drm/i915/i915_gem.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4999,6 +4999,16 @@ i915_gem_load(struct drm_device *dev) list_add(&dev_priv->mm.shrink_list, &shrink_list); spin_unlock(&shrink_list_lock); + /* On GEN3 we really need to make sure the ARB C3 LP bit is set */ + if (IS_GEN3(dev)) { + u32 tmp = I915_READ(MI_ARB_STATE); + if (!(tmp & MI_ARB_C3_LP_WRITE_ENABLE)) { + /* arb state is a masked write, so set bit + bit in mask */ + tmp = MI_ARB_C3_LP_WRITE_ENABLE | (MI_ARB_C3_LP_WRITE_ENABLE << MI_ARB_MASK_SHIFT); + I915_WRITE(MI_ARB_STATE, tmp); + } + } + /* Old X drivers will take 0-2 for front, back, depth buffers */ dev_priv->fence_reg_start = 3;
|