[Intel-gfx] [PATCH] drm/i915: Remove too early plane enable on pre-PCH hardware

[Jesse Barnes]

On Tue, 24 Apr 2012 16:36:50 +0100
Chris Wilson <chris at chris-wilson.co.uk> wrote:

> Enabling the plane before we have assigned valid address means that it
> will access random PTE (often with conflicting memory types) and cause
> GPU lockups. However, enabling the plane too early appears to workaround
> a number of bugs in our modesetting code.
> 
> Cc: Franz Melchior <melchior.franz at gmail.com>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=39947
> References: https://bugs.freedesktop.org/show_bug.cgi?id=41091
> References: https://bugs.freedesktop.org/show_bug.cgi?id=49041
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_display.c |    1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 45e668c..c2d7a82 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4025,7 +4025,6 @@ static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
>  
>  	I915_WRITE(DSPCNTR(plane), dspcntr);
>  	POSTING_READ(DSPCNTR(plane));
> -	intel_enable_plane(dev_priv, plane, pipe);
>  
>  	ret = intel_pipe_set_base(crtc, x, y, old_fb);
>  

Acked-by: Jesse Barnes <jbarnes at virtuousgeek.org>

If this introduces regressions in mode setting, I think it means we
still have a serious bug hiding in the 9xx stuff somewhere that we
ought to root cause instead of papering over again.

-- 
Jesse Barnes, Intel Open Source Technology Center