Re: 2.6.32 regression (bisected): Video tearing/glitching withT400 laptops

From: Carlos R. Mafra
Date: Mon Oct 12 2009 - 14:49:47 EST


On Mon 12.Oct'09 at 9:54:38 -0700, Jesse Barnes wrote:
> >
> > Nope, unfortunately, it's not helping on my T400 laptop. I'm still
> > getting huge amounts of glitching and tearing with this patch applied
> > against -rc3.
> >
> > What I'm using for now to fix up my system is this patch.
> >
>
> How about this one? I have one more idea to try out if this doesn't
> work (hacking on it now).

I was also experiencing something very similar to Theodore's bug
report and, at least for me, the patch below fixed the issue (the
previous one also had no effect).


> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7a5fb79..1451945 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -1047,7 +1047,7 @@ static void g4x_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
> dev_priv->cfb_fence = obj_priv->fence_reg;
> dev_priv->cfb_plane = intel_crtc->plane;
>
> - dpfc_ctl = plane | DPFC_SR_EN | DPFC_CTL_LIMIT_1X;
> + dpfc_ctl = plane | DPFC_CTL_LIMIT_1X;
> if (obj_priv->tiling_mode != I915_TILING_NONE) {
> dpfc_ctl |= DPFC_CTL_FENCE_EN | dev_priv->cfb_fence;
> I915_WRITE(DPFC_CHICKEN, DPFC_HT_MODIFY);
> --

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