Re: [PATCH 1/2] drm/i915: Do forcewake reset on gen8

[Ben Widawsky <ben@bwidawsk.net>]

On Wed, Feb 19, 2014 at 06:59:25PM +0200, mika.kuoppala@intel.com wrote:
> From: Mika Kuoppala <mika.kuoppala@intel.com>
> 
> When we get control from BIOS there might be mt forcewake
> bits already set. Apparently double write into mt forcewake
> without proper clear/ack sequence in between will cause
> system hang.
> 

I'd remove the bit about the hang, since we can't really explain it, and
while I am at it, I'd remove it from the previous patch I reviewed to,
but whatever.

> Fix this by clearing mt forcewake register on init,
> like we do with older gens.
> 
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>

Either way:
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

> ---
>  drivers/gpu/drm/i915/intel_uncore.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index c628414..25ceac4 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -305,13 +305,13 @@ static void intel_uncore_forcewake_reset(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
> -	if (IS_VALLEYVIEW(dev)) {
> +	if (IS_VALLEYVIEW(dev))
>  		vlv_force_wake_reset(dev_priv);
> -	} else if (INTEL_INFO(dev)->gen >= 6) {
> +	else if (IS_GEN6(dev) || IS_GEN7(dev))
>  		__gen6_gt_force_wake_reset(dev_priv);
> -		if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev))
> -			__gen6_gt_force_wake_mt_reset(dev_priv);
> -	}
> +
> +	if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev) || IS_GEN8(dev))
> +		__gen6_gt_force_wake_mt_reset(dev_priv);
>  }
>  
>  void intel_uncore_early_sanitize(struct drm_device *dev)
> -- 
> 1.7.9.5
> 
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-- 
Ben Widawsky, Intel Open Source Technology Center