[Intel-gfx] [PATCH] drm/i915: Protect older gen against intel_gt_init_powersave()

[Joonas Lahtinen]

On ti, 2016-08-02 at 13:55 +0300, Ville Syrjälä wrote:
> On Tue, Aug 02, 2016 at 11:15:27AM +0100, Chris Wilson wrote:
> > 
> > In the middle of intel_gt_init_powersave() we have an if-chain that ends
> > with a universal else clause to read gen6+ registers. Older platforms
> > like Pineview that end up here do not like those registers and may even
> > OOPS whilst reading them!
> > 
> > Fixes: 3a45b05c4517 ("drm/i915: Preserve current RPS frequency across init")
> Shouldn't that be
> Fixes: 773ea9a80132 ("drm/i915: Perform static RPS frequency setup before userspace") ?
> 

Me thinks so too, the patch in original Fixes: is the one that
triggered the bug in bisecting(?), but patch that Ville mentioned is
what should be followed by this patch everywhere being applied, so the
Fixes: should point to it.

So with above Fixes: updated.

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas

> Either way,
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 1ac32428d4db..86e136c23ac2 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -6493,7 +6493,7 @@ void intel_init_gt_powersave(struct drm_i915_private *dev_priv)
> >  		cherryview_init_gt_powersave(dev_priv);
> >  	else if (IS_VALLEYVIEW(dev_priv))
> >  		valleyview_init_gt_powersave(dev_priv);
> > -	else
> > +	else if (INTEL_GEN(dev_priv) >= 6)
> >  		gen6_init_rps_frequencies(dev_priv);
> >  
> >  	/* Derive initial user preferences/limits from the hardware limits */
> > -- 
> > 2.8.1
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation