[Intel-gfx] [PATCH v2] drm/i915: Fix init_clock_gating for resume

[Chris Wilson]

Quoting Ville Syrjala (2017-11-16 16:02:15)
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Moving the init_clock_gating() call from intel_modeset_init_hw() to
> intel_modeset_gem_init() had an unintended effect of not applying
> some workarounds on resume. This, for example, cause some kind of
> corruption to appear at the top of my IVB Thinkpad X1 Carbon LVDS
> screen after hibernation. Fix the problem by explicitly calling
> init_clock_gating() from the resume path.
> 
> I really hope this doesn't break something else again. At least
> the problems reported at https://bugs.freedesktop.org/show_bug.cgi?id=103549
> didn't make a comeback, even after a hibernate cycle.
> 
> v2: Reorder the init_clock_gating vs. modeset_init_hw to match
>     the display reset path (Rodrigo)
> 
> Cc: stable at vger.kernel.org
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Fixes: 6ac43272768c ("drm/i915: Move init_clock_gating() back to where it was")
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 3423d873123a..fb584b821fb3 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1709,6 +1709,7 @@ static int i915_drm_resume(struct drm_device *dev)
>         i915_gem_resume(dev_priv);
>  
>         intel_modeset_init_hw(dev);
> +       intel_init_clock_gating(dev_priv);

The repetition of GT stuff here shouldn't be a problem, since they
should match the values in the reloaded context. (If not, we have bigger
problems!) And the bits that aren't in the context do need to be
restored.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris