From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Widawsky <ben@bwidawsk.net>
Subject: Re: [PATCH] xdrm/i915: Respect HW RC6 states
 availability
Date: Wed, 24 Oct 2012 22:31:01 -0700
Message-ID: <20121024223101.000041b4@unknown>
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To: Rodrigo Vivi <rodrigo.vivi@gmail.com>
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On Wed, 24 Oct 2012 20:05:15 -0200
Rodrigo Vivi <rodrigo.vivi@gmail.com> wrote:

> If Hardware doesn't allow RC6p or RC6pp we shall avoid end users
> turning them on, falling back to the only RC6 deepness available.
> 
> v2: fixed "if" comparison pointed by Chris Wilson
> 

For future reference, putting "v2" in the title is often helpful in
situations like this.

> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c
> b/drivers/gpu/drm/i915/intel_pm.c index 50f5809..b6362d0 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -2370,7 +2370,7 @@ static void gen6_disable_rps(struct drm_device
> *dev) int intel_enable_rc6(const struct drm_device *dev)
>  {
>  	/* Respect the kernel parameter if it is set */
> -	if (i915_enable_rc6 >= 0)
> +	if (i915_enable_rc6 == 0)
>  		return i915_enable_rc6;
>  
>  	if (INTEL_INFO(dev)->gen == 5) {
> @@ -2394,6 +2394,9 @@ int intel_enable_rc6(const struct drm_device
> *dev) return INTEL_RC6_ENABLE;
>  	}
>  
> +	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);
>  }

I like the direction this patch is going but I think it does limit
people with knowledge might want to do (for instance, I ran with rc6
on ILK just fine for quite a while).

How about we use add_taint instead, and a printk with KERN_WARNING for
platforms which have known issues?