Re: [PATCH 3/2] drm/i915: Streamline VLV forcewake handling

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

On Fri, Feb 28, 2014 at 07:56:56PM +0530, S, Deepak wrote:
> 
> 
> On 2/28/2014 1:37 AM, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > It occured to me that when we're trying to wake up both render
> > and media wells on VLV, we might end up calling the low level
> > force_wake_get/put two times even though one call would be
> > enough. Make that happen by figuring out which wells really
> > need to be woken up based on the forcewake counts.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >   drivers/gpu/drm/i915/intel_uncore.c | 70 +++++++++++++++----------------------
> >   1 file changed, 29 insertions(+), 41 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> > index dacb751..4119ddc 100644
> > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > @@ -251,16 +251,16 @@ void vlv_force_wake_get(struct drm_i915_private *dev_priv,
> >   	unsigned long irqflags;
> >
> >   	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> > -	if (FORCEWAKE_RENDER & fw_engine) {
> > -		if (dev_priv->uncore.fw_rendercount++ == 0)
> > -			dev_priv->uncore.funcs.force_wake_get(dev_priv,
> > -							FORCEWAKE_RENDER);
> > -	}
> > -	if (FORCEWAKE_MEDIA & fw_engine) {
> > -		if (dev_priv->uncore.fw_mediacount++ == 0)
> > -			dev_priv->uncore.funcs.force_wake_get(dev_priv,
> > -							FORCEWAKE_MEDIA);
> > -	}
> > +
> > +	if (fw_engine & FORCEWAKE_RENDER &&
> > +	    dev_priv->uncore.fw_rendercount++ != 0)
> > +		fw_engine &= ~FORCEWAKE_RENDER;
> > +	if (fw_engine & FORCEWAKE_MEDIA &&
> > +	    dev_priv->uncore.fw_mediacount++ != 0)
> > +		fw_engine &= ~FORCEWAKE_MEDIA;
> 
> Should  we add WARN_ON? I think it will help us if we have forcewake 
> count mismatch?
> 
> Other than this. Patch looks good.
> Reviewed-by:Deepak S <deepak.s@intel.com>

I dropped the WARNs since we didn't have them on other platforms either.
But if people think they might help, I'm not opposed to keeping them.

> 
> > +	if (fw_engine)
> > +		dev_priv->uncore.funcs.force_wake_get(dev_priv, fw_engine);
> >
> >   	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> >   }
> > @@ -272,19 +272,15 @@ void vlv_force_wake_put(struct drm_i915_private *dev_priv,
> >
> >   	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> >
> > -	if (FORCEWAKE_RENDER & fw_engine) {
> > -		WARN_ON(dev_priv->uncore.fw_rendercount == 0);
> > -		if (--dev_priv->uncore.fw_rendercount == 0)
> > -			dev_priv->uncore.funcs.force_wake_put(dev_priv,
> > -							FORCEWAKE_RENDER);
> > -	}
> > +	if (fw_engine & FORCEWAKE_RENDER &&
> > +	    --dev_priv->uncore.fw_rendercount != 0)
> > +		fw_engine &= ~FORCEWAKE_RENDER;
> > +	if (fw_engine & FORCEWAKE_MEDIA &&
> > +	    --dev_priv->uncore.fw_mediacount != 0)
> > +		fw_engine &= ~FORCEWAKE_MEDIA;
> >
> > -	if (FORCEWAKE_MEDIA & fw_engine) {
> > -		WARN_ON(dev_priv->uncore.fw_mediacount == 0);
> > -		if (--dev_priv->uncore.fw_mediacount == 0)
> > -			dev_priv->uncore.funcs.force_wake_put(dev_priv,
> > -							FORCEWAKE_MEDIA);
> > -	}
> > +	if (fw_engine)
> > +		dev_priv->uncore.funcs.force_wake_put(dev_priv, fw_engine);
> >
> >   	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> >   }
> > @@ -502,27 +498,19 @@ gen6_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
> >   static u##x \
> >   vlv_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
> >   	unsigned fwengine = 0; \
> > -	unsigned fwcount; \
> >   	REG_READ_HEADER(x); \
> > -	if (FORCEWAKE_VLV_RENDER_RANGE_OFFSET(reg)) {   \
> > -		fwengine = FORCEWAKE_RENDER;            \
> > -		fwcount = dev_priv->uncore.fw_rendercount;    \
> > -	}                                               \
> > -	else if (FORCEWAKE_VLV_MEDIA_RANGE_OFFSET(reg)) {       \
> > -		fwengine = FORCEWAKE_MEDIA;             \
> > -		fwcount = dev_priv->uncore.fw_mediacount;     \
> > +	if (FORCEWAKE_VLV_RENDER_RANGE_OFFSET(reg)) { \
> > +		if (dev_priv->uncore.fw_rendercount == 0) \
> > +			fwengine = FORCEWAKE_RENDER; \
> > +	} else if (FORCEWAKE_VLV_MEDIA_RANGE_OFFSET(reg)) { \
> > +		if (dev_priv->uncore.fw_mediacount == 0) \
> > +			fwengine = FORCEWAKE_MEDIA; \
> >   	}  \
> > -	if (fwengine != 0) {		\
> > -		if (fwcount == 0) \
> > -			(dev_priv)->uncore.funcs.force_wake_get(dev_priv, \
> > -								fwengine); \
> > -		val = __raw_i915_read##x(dev_priv, reg); \
> > -		if (fwcount == 0) \
> > -			(dev_priv)->uncore.funcs.force_wake_put(dev_priv, \
> > -							fwengine); \
> > -	} else { \
> > -		val = __raw_i915_read##x(dev_priv, reg); \
> > -	} \
> > +	if (fwengine) \
> > +		dev_priv->uncore.funcs.force_wake_get(dev_priv, fwengine); \
> > +	val = __raw_i915_read##x(dev_priv, reg); \
> > +	if (fwengine) \
> > +		dev_priv->uncore.funcs.force_wake_put(dev_priv, fwengine); \
> >   	REG_READ_FOOTER; \
> >   }
> >
> >

-- 
Ville Syrjälä
Intel OTC