Re: [PATCH] drm/i915: Consolidate forcewake resetting to a single function

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> We have two paths that try to reset the forcewake registers back to
> known good values, with slightly different semantics and levels of
> paranoia. Combine the two by passing a parameter to either restore the
> forcewake status or to clear our bookkeeping, and raise the paranoia
> level to max.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_uncore.c | 81 +++++++++++++++++++------------------
>  1 file changed, 41 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 361d1eae3cfd..e6bb421a3dbd 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -308,9 +308,17 @@ static void gen6_force_wake_timer(unsigned long arg)
>  	intel_runtime_pm_put(dev_priv);
>  }
>  
> -static void intel_uncore_forcewake_reset(struct drm_device *dev)
> +static void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +	unsigned long irqflags;
> +
> +	del_timer_sync(&dev_priv->uncore.force_wake_timer);
> +
> +	/* Hold uncore.lock across reset to prevent any register access
> +	 * with forcewake not set correctly
> +	 */
> +	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
>  
>  	if (IS_VALLEYVIEW(dev))
>  		vlv_force_wake_reset(dev_priv);
> @@ -319,6 +327,35 @@ static void intel_uncore_forcewake_reset(struct drm_device *dev)
>  
>  	if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev) || IS_GEN8(dev))
>  		__gen7_gt_force_wake_mt_reset(dev_priv);
> +
> +	if (restore) { /* If reset with a user forcewake, try to restore */
> +		unsigned fw = 0;
> +
> +		if (IS_VALLEYVIEW(dev)) {
> +			if (dev_priv->uncore.fw_rendercount)
> +				fw |= FORCEWAKE_RENDER;
> +
> +			if (dev_priv->uncore.fw_mediacount)
> +				fw |= FORCEWAKE_MEDIA;
> +		} else {
> +			if (dev_priv->uncore.forcewake_count)
> +				fw = FORCEWAKE_ALL;
> +		}
> +
> +		if (fw)
> +			dev_priv->uncore.funcs.force_wake_get(dev_priv, fw);
> +
> +		if (IS_GEN6(dev) || IS_GEN7(dev))
> +			dev_priv->uncore.fifo_count =
> +				__raw_i915_read32(dev_priv, GTFIFOCTL) &
> +				GT_FIFO_FREE_ENTRIES_MASK;
> +	} else {
> +		dev_priv->uncore.forcewake_count = 0;
> +		dev_priv->uncore.fw_rendercount = 0;
> +		dev_priv->uncore.fw_mediacount = 0;
> +	}
> +
> +	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
>  
>  void intel_uncore_early_sanitize(struct drm_device *dev)
> @@ -344,7 +381,7 @@ void intel_uncore_early_sanitize(struct drm_device *dev)
>  		__raw_i915_write32(dev_priv, GTFIFODBG,
>  				   __raw_i915_read32(dev_priv, GTFIFODBG));
>  
> -	intel_uncore_forcewake_reset(dev);
> +	intel_uncore_forcewake_reset(dev, false);
>  }
>  
>  void intel_uncore_sanitize(struct drm_device *dev)
> @@ -798,17 +835,9 @@ void intel_uncore_init(struct drm_device *dev)
>  
>  void intel_uncore_fini(struct drm_device *dev)
>  {
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -
> -	del_timer_sync(&dev_priv->uncore.force_wake_timer);
> -
>  	/* Paranoia: make sure we have disabled everything before we exit. */
>  	intel_uncore_sanitize(dev);
> -	intel_uncore_forcewake_reset(dev);
> -
> -	dev_priv->uncore.forcewake_count = 0;
> -	dev_priv->uncore.fw_rendercount = 0;
> -	dev_priv->uncore.fw_mediacount = 0;
> +	intel_uncore_forcewake_reset(dev, false);
>  }
>  
>  static const struct register_whitelist {
> @@ -957,13 +986,6 @@ 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
> -	 */
> -	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
>  
>  	/* Reset the chip */
>  
> @@ -976,29 +998,8 @@ static int gen6_do_reset(struct drm_device *dev)
>  	/* Spin waiting for the device to ack the reset request */
>  	ret = wait_for((__raw_i915_read32(dev_priv, GEN6_GDRST) & GEN6_GRDOM_FULL) == 0, 500);

We used to go through the reset with uncore lock held,
which is not the case anymore. Will it create problems?

-Mika

> -	intel_uncore_forcewake_reset(dev);
> -
> -	/* If reset with a user forcewake, try to restore */
> -	if (IS_VALLEYVIEW(dev)) {
> -		if (dev_priv->uncore.fw_rendercount)
> -			fw_engine |= FORCEWAKE_RENDER;
> -
> -		if (dev_priv->uncore.fw_mediacount)
> -			fw_engine |= FORCEWAKE_MEDIA;
> -	} else {
> -		if (dev_priv->uncore.forcewake_count)
> -			fw_engine = FORCEWAKE_ALL;
> -	}
> -
> -	if (fw_engine)
> -		dev_priv->uncore.funcs.force_wake_get(dev_priv, fw_engine);
> +	intel_uncore_forcewake_reset(dev, true);
>  
> -	if (IS_GEN6(dev) || IS_GEN7(dev))
> -		dev_priv->uncore.fifo_count =
> -			__raw_i915_read32(dev_priv, GTFIFOCTL) &
> -			GT_FIFO_FREE_ENTRIES_MASK;
> -
> -	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  	return ret;
>  }
>  
> -- 
> 1.9.0
>
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