Re: [PATCH] drm/i915: Clear FORCEWAKE when taking over from BIOS

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

On Thu, 18 Oct 2012 11:46:10 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote:

> Some BIOSes may forcibly suspend RC6 during their operation which
> trigger a warning as we find the hardware in a perplexing state upon
> first use. So far that appears to be the worst symptom as fortuituously
> we use the same values as the BIOS for programming the FORCEWAKE register.
> 
> Reported-by: <bug-track@fisher-privat.net>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_drv.c |    2 ++
>  drivers/gpu/drm/i915/i915_drv.h |    1 +
>  drivers/gpu/drm/i915/intel_pm.c |   32 ++++++++++++++++++++++++++++++++
>  3 files changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 705b2e1..ea2b718 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -526,6 +526,8 @@ static int i915_drm_thaw(struct drm_device *dev)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	int error = 0;
>  
> +	intel_gt_reset(dev);
> +
>  	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
>  		mutex_lock(&dev->struct_mutex);
>  		i915_gem_restore_gtt_mappings(dev);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 2b7f07b..3a0c102 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1300,6 +1300,7 @@ void i915_handle_error(struct drm_device *dev, bool wedged);
>  
>  extern void intel_irq_init(struct drm_device *dev);
>  extern void intel_gt_init(struct drm_device *dev);
> +extern void intel_gt_reset(struct drm_device *dev);
>  
>  void i915_error_state_free(struct kref *error_ref);
>  
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 423ee69..fbdb104 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3999,6 +3999,12 @@ static void __gen6_gt_wait_for_thread_c0(struct drm_i915_private *dev_priv)
>  		DRM_ERROR("GT thread status wait timed out\n");
>  }
>  
> +static void __gen6_gt_force_wake_reset(struct drm_i915_private *dev_priv)
> +{
> +	I915_WRITE_NOTRACE(FORCEWAKE, 0);
> +	POSTING_READ(ECOBUS); /* something from same cacheline, but !FORCEWAKE */
> +}
> +
>  static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
>  {
>  	u32 forcewake_ack;
> @@ -4022,6 +4028,12 @@ static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
>  	__gen6_gt_wait_for_thread_c0(dev_priv);
>  }
>  
> +static void __gen6_gt_force_wake_mt_reset(struct drm_i915_private *dev_priv)
> +{
> +	I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_DISABLE(0xffff));
> +	POSTING_READ(ECOBUS); /* something from same cacheline, but !FORCEWAKE */
> +}
> +
>  static void __gen6_gt_force_wake_mt_get(struct drm_i915_private *dev_priv)
>  {
>  	u32 forcewake_ack;
> @@ -4117,6 +4129,11 @@ int __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
>  	return ret;
>  }
>  
> +static void vlv_force_wake_reset(struct drm_i915_private *dev_priv)
> +{
> +	I915_WRITE_NOTRACE(FORCEWAKE_VLV, _MASKED_BIT_DISABLE(0xffff));
> +}
> +
>  static void vlv_force_wake_get(struct drm_i915_private *dev_priv)
>  {
>  	if (wait_for_atomic((I915_READ_NOTRACE(FORCEWAKE_ACK_VLV) & 1) == 0,
> @@ -4139,12 +4156,27 @@ static void vlv_force_wake_put(struct drm_i915_private *dev_priv)
>  	gen6_gt_check_fifodbg(dev_priv);
>  }
>  
> +void intel_gt_reset(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;

Would it be possible to call in here:

      if (HAS_FORCE_WAKE(dev))
         dev_priv->gt.force_wake_put(dev_priv);

and get rid of the per gen forcewake resets?

> +
> +	if (IS_VALLEYVIEW(dev)) {
> +		vlv_force_wake_reset(dev_priv);
> +	} else if (INTEL_INFO(dev)->gen >= 6) {
> +		__gen6_gt_force_wake_reset(dev_priv);
> +		if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev))
> +			__gen6_gt_force_wake_mt_reset(dev_priv);
> +	}
> +}
>  void intel_gt_init(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
>  	spin_lock_init(&dev_priv->gt_lock);
>  
> +	intel_gt_reset(dev);
> +
>  	if (IS_VALLEYVIEW(dev)) {
>  		dev_priv->gt.force_wake_get = vlv_force_wake_get;
>  		dev_priv->gt.force_wake_put = vlv_force_wake_put;
> -- 
> 1.7.10.4
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