[Intel-gfx] [PATCH 09/10] drm/i915: Implement WaRsDisableRC6Plus

[Paulo Zanoni]

2013/6/7 Damien Lespiau <damien.lespiau at intel.com>:
> Let's disable RC6+ by default. We still leave the possibility to
> override this with the module parameter.
>
> I've also shuffled the code around so we always log if we have RC6
> enabled or disabled.

Why disable RC6+ on IVB? My docs tells me it should only be disabled
on the very first pre-production machines that no one has. On the
other hand, it looks like that for VLV we should disable RC6+.

The "code shuffle" looks like a nice improvement.

>
> Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 25 +++++++++----------------
>  1 file changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 0465cd6..e19952f 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3158,27 +3158,20 @@ int intel_enable_rc6(const struct drm_device *dev)
>         if (INTEL_INFO(dev)->gen < 5)
>                 return 0;
>
> -       /* Respect the kernel parameter if it is set */
> -       if (i915_enable_rc6 >= 0)
> -               return i915_enable_rc6;
> -
>         /* Disable RC6 on Ironlake */
> -       if (INTEL_INFO(dev)->gen == 5)
> +       if (i915_enable_rc6 == 0 || INTEL_INFO(dev)->gen == 5) {
> +               DRM_DEBUG_DRIVER("RC6 disabled\n");
>                 return 0;
> -
> -       if (IS_HASWELL(dev)) {
> -               DRM_DEBUG_DRIVER("Haswell: only RC6 available\n");
> -               return INTEL_RC6_ENABLE;
>         }
>
> -       /* snb/ivb have more than one rc6 state. */
> -       if (INTEL_INFO(dev)->gen == 6) {
> -               DRM_DEBUG_DRIVER("Sandybridge: deep RC6 disabled\n");
> -               return INTEL_RC6_ENABLE;
> -       }
> +       DRM_DEBUG_DRIVER("RC6 enabled\n");
> +
> +       if (i915_enable_rc6 > 0)
> +               return i915_enable_rc6;
>
> -       DRM_DEBUG_DRIVER("RC6 and deep RC6 enabled\n");
> -       return (INTEL_RC6_ENABLE | INTEL_RC6p_ENABLE);
> +       /* snb/ivb have more than one rc6 state. However we only allow RC6
> +        * WaRsDisableRC6Plus:snb,ivb,vlv */
> +       return INTEL_RC6_ENABLE;
>  }
>
>  static void gen6_enable_rps(struct drm_device *dev)
> --
> 1.8.1.4
>
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-- 
Paulo Zanoni