Re: [PATCH] drm/i915: Wait old forcewake ack to clear on vlv

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Nov 05, 2014 at 10:18:46AM +0200, Mika Kuoppala wrote:
> Don't rush into getting new fw until the clearing
> of old one has been acked.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85684
> Tested-by: lu hua <huax.lu@intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>

This is just a revert of 
 commit 5cb13c07dae73380d8b3ddc792740487b8742938
 Author: Deepak S <deepak.s@linux.intel.com>
 Date:   Thu Sep 18 18:51:50 2014 +0530

    drm/i915/vlv: Remove check for Old Ack during forcewake

except you left the comment behind.

Would be nice to have some kind of real explanation what is going on
here. Deepak, any ideas?

> ---
>  drivers/gpu/drm/i915/intel_uncore.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 9427641..5259b38 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -204,6 +204,10 @@ static void __vlv_force_wake_get(struct drm_i915_private *dev_priv,
>  	/* Check for Render Engine */
>  	if (FORCEWAKE_RENDER & fw_engine) {
>  
> +		if (wait_for_atomic((__raw_i915_read32(dev_priv, FORCEWAKE_ACK_VLV) &
> +				     FORCEWAKE_KERNEL) == 0, FORCEWAKE_ACK_TIMEOUT_MS))
> +			DRM_ERROR("Timed out: waiting for old Render ack to clear.\n");
> +
>  		__raw_i915_write32(dev_priv, FORCEWAKE_VLV,
>  				   _MASKED_BIT_ENABLE(FORCEWAKE_KERNEL));
>  
> @@ -217,6 +221,11 @@ static void __vlv_force_wake_get(struct drm_i915_private *dev_priv,
>  	/* Check for Media Engine */
>  	if (FORCEWAKE_MEDIA & fw_engine) {
>  
> +		if (wait_for_atomic((__raw_i915_read32(dev_priv, FORCEWAKE_ACK_MEDIA_VLV) &
> +				     FORCEWAKE_KERNEL) == 0, FORCEWAKE_ACK_TIMEOUT_MS))
> +			DRM_ERROR("Timed out: waiting for old media ack to clear.\n");
> +
> +
>  		__raw_i915_write32(dev_priv, FORCEWAKE_MEDIA_VLV,
>  				   _MASKED_BIT_ENABLE(FORCEWAKE_KERNEL));
>  
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC
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