Re: [PATCH 1/2] drm/i915: No need to put forcewake after a reset

[Ben Widawsky <ben@bwidawsk.net>]

On Wed, Mar 05, 2014 at 06:08:18PM +0200, Mika Kuoppala wrote:
> As we now have intel_uncore_forcewake_reset() no need
> to do explicit put after reset.
> 
> v2: rebase
> 
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_uncore.c |   19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 6ca24ac..00320fd 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -952,6 +952,7 @@ static int gen6_do_reset(struct drm_device *dev)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	int	ret;
>  	unsigned long irqflags;
> +	u32 fw_engine = 0;
>  
>  	/* Hold uncore.lock across reset to prevent any register access
>  	 * with forcewake not set correctly
> @@ -971,25 +972,21 @@ static int gen6_do_reset(struct drm_device *dev)
>  
>  	intel_uncore_forcewake_reset(dev);
>  
> -	/* If reset with a user forcewake, try to restore, otherwise turn it off */
> +	/* If reset with a user forcewake, try to restore */

Technically with the introduction of the deferred forcewaker_ put, it's
not just user forcewake that this restores.

Wouldn't it be nice if we actually used something other than
FORCEWAKE_KERNEL for debugfs?

>  	if (IS_VALLEYVIEW(dev)) {
>  		if (dev_priv->uncore.fw_rendercount)
> -			dev_priv->uncore.funcs.force_wake_get(dev_priv, FORCEWAKE_RENDER);
> -		else
> -			dev_priv->uncore.funcs.force_wake_put(dev_priv, FORCEWAKE_RENDER);
> +			fw_engine |= FORCEWAKE_RENDER;
>  
>  		if (dev_priv->uncore.fw_mediacount)
> -			dev_priv->uncore.funcs.force_wake_get(dev_priv, FORCEWAKE_MEDIA);
> -		else
> -			dev_priv->uncore.funcs.force_wake_put(dev_priv, FORCEWAKE_MEDIA);
> +			fw_engine |= FORCEWAKE_MEDIA;
>  	} else {
>  		if (dev_priv->uncore.forcewake_count)
> -			dev_priv->uncore.funcs.force_wake_get(dev_priv, FORCEWAKE_ALL);
> -		else
> -			dev_priv->uncore.funcs.force_wake_put(dev_priv, FORCEWAKE_ALL);
> +			fw_engine = FORCEWAKE_ALL;
>  	}

P

>  
> -	/* Restore fifo count */
> +	if (fw_engine)
> +		dev_priv->uncore.funcs.force_wake_get(dev_priv, fw_engine);
> +
>  	if (IS_GEN6(dev) || IS_GEN7(dev))
>  		dev_priv->uncore.fifo_count =
>  			__raw_i915_read32(dev_priv, GTFIFOCTL) &

I for one would not be opposed to a vlv_do_reset() and a
gen8_do_reset(). I implemented such a thing at some point, but threw it
away because I didn't actually have a vlv diff at the time.

I had to re-review a lot of the uncore.lock stuff, but lgtm:
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

-- 
Ben Widawsky, Intel Open Source Technology Center