Re: [PATCH 01/10] drm/i915/bdw: Implement a basic PM interrupt handler

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

On Mon, May 05, 2014 at 06:17:30PM +0530, deepak.s@linux.intel.com wrote:
> From: Ben Widawsky <benjamin.widawsky@intel.com>
> 
> Almost all of it is reusable from the existing code. The primary
> difference is we need to do even less in the interrupt handler, since
> interrupts are not shared in the same way.
> 
> The patch is mostly a copy-paste of the existing snb+ code, with updates
> to the relevant parts requiring changes to the interrupt handling. As
> such it /should/ be relatively trivial. It's highly likely that I missed
> some places where I need a gen8 version of the PM interrupts, but it has
> become invisible to me by now.
> 
> This patch could probably be split into adding the new functions,
> followed by actually handling the interrupts. Since the code is
> currently disabled (and broken) I think the patch stands better by
> itself.
> 
> v2: Move the commit about not touching the ringbuffer interrupt to the
> snb_* function where it belongs (Rodrigo)
> 
> v3: Rebased on Paulo's runtime PM changes
> 
> v4: Not well validated, but rebase on
> commit 730488b2eddded4497f63f70867b1256cd9e117c
> Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Date:   Fri Mar 7 20:12:32 2014 -0300
> 
>     drm/i915: kill dev_priv->pm.regsave
> 
> v5: Rebased on latest code base. (Deepak)
> 
> v6: Remove conflict markers, Unnecessary empty line and use right
> IIR interrupt (Ville)
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> Signed-off-by: Deepak S <deepak.s@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c  | 75 ++++++++++++++++++++++++++++++++++++++--
>  drivers/gpu/drm/i915/i915_reg.h  |  1 +
>  drivers/gpu/drm/i915/intel_drv.h |  2 ++
>  drivers/gpu/drm/i915/intel_pm.c  | 38 ++++++++++++++++++--
>  4 files changed, 112 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 2d76183..6af51ad 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -248,6 +248,49 @@ static bool ivb_can_enable_err_int(struct drm_device *dev)
>  	return true;
>  }
>  
> +/**
> +  * bdw_update_pm_irq - update GT interrupt 2
> +  * @dev_priv: driver private
> +  * @interrupt_mask: mask of interrupt bits to update
> +  * @enabled_irq_mask: mask of interrupt bits to enable
> +  *
> +  * Copied from the snb function, updated with relevant register offsets
> +  */
> +static void bdw_update_pm_irq(struct drm_i915_private *dev_priv,
> +			      uint32_t interrupt_mask,
> +			      uint32_t enabled_irq_mask)
> +{
> +	uint32_t new_val;
> +
> +	assert_spin_locked(&dev_priv->irq_lock);
> +
> +	if (dev_priv->pm.irqs_disabled) {
> +		WARN(1, "IRQs disabled\n");
> +		return;
> +	}

Could be just 'if (WARN...' just like in the snb function.

> +
> +	new_val = dev_priv->pm_irq_mask;
> +	new_val &= ~interrupt_mask;
> +	new_val |= (~enabled_irq_mask & interrupt_mask);
> +
> +	if (new_val != dev_priv->pm_irq_mask) {
> +		dev_priv->pm_irq_mask = new_val;
> +		I915_WRITE(GEN8_GT_IMR(2), I915_READ(GEN8_GT_IMR(2)) |
> +					   dev_priv->pm_irq_mask);

I just realized that this doesn't actually clear the old bits. I think
we should just kill the RMW here and mandate that all users of GT_IMR(2)
need to use this function.

Also you're forgetting to initialize pm_irq_mask. I guess it should be
initialized in gen8_gt_irq_postinstall() to match the gen6 code.

> +		POSTING_READ(GEN8_GT_IMR(2));
> +	}
> +}
> +
> +void bdw_enable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask)
> +{
> +	bdw_update_pm_irq(dev_priv, mask, mask);
> +}
> +
> +void bdw_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask)
> +{
> +	bdw_update_pm_irq(dev_priv, mask, 0);
> +}
> +
>  static bool cpt_can_enable_serr_int(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -1098,8 +1141,12 @@ static void gen6_pm_rps_work(struct work_struct *work)
>  	spin_lock_irq(&dev_priv->irq_lock);
>  	pm_iir = dev_priv->rps.pm_iir;
>  	dev_priv->rps.pm_iir = 0;
> -	/* Make sure not to corrupt PMIMR state used by ringbuffer code */
> -	snb_enable_pm_irq(dev_priv, dev_priv->pm_rps_events);
> +	if (IS_BROADWELL(dev_priv->dev))
> +		bdw_enable_pm_irq(dev_priv, dev_priv->pm_rps_events);
> +	else {
> +		/* Make sure not to corrupt PMIMR state used by ringbuffer */
> +		snb_enable_pm_irq(dev_priv, dev_priv->pm_rps_events);
> +	}
>  	spin_unlock_irq(&dev_priv->irq_lock);
>  
>  	/* Make sure we didn't queue anything we're not going to process. */
> @@ -1296,6 +1343,19 @@ static void snb_gt_irq_handler(struct drm_device *dev,
>  		ivybridge_parity_error_irq_handler(dev, gt_iir);
>  }
>  
> +static void gen8_rps_irq_handler(struct drm_i915_private *dev_priv, u32 pm_iir)
> +{
> +	if ((pm_iir & dev_priv->pm_rps_events) == 0)
> +		return;
> +
> +	spin_lock(&dev_priv->irq_lock);
> +	dev_priv->rps.pm_iir |= pm_iir & dev_priv->pm_rps_events;
> +	bdw_disable_pm_irq(dev_priv, pm_iir & dev_priv->pm_rps_events);
> +	spin_unlock(&dev_priv->irq_lock);
> +
> +	queue_work(dev_priv->wq, &dev_priv->rps.work);
> +}
> +
>  static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
>  				       struct drm_i915_private *dev_priv,
>  				       u32 master_ctl)
> @@ -1334,6 +1394,17 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
>  			DRM_ERROR("The master control interrupt lied (GT1)!\n");
>  	}
>  
> +	if (master_ctl & GEN8_GT_PM_IRQ) {
> +		tmp = I915_READ(GEN8_GT_IIR(2));
> +		if (tmp & dev_priv->pm_rps_events) {
> +			ret = IRQ_HANDLED;
> +			gen8_rps_irq_handler(dev_priv, tmp);
> +			I915_WRITE(GEN8_GT_IIR(2),
> +				   tmp & dev_priv->pm_rps_events);
> +		} else
> +			DRM_ERROR("The master control interrupt lied (PM)!\n");
> +	}
> +
>  	if (master_ctl & GEN8_GT_VECS_IRQ) {
>  		tmp = I915_READ(GEN8_GT_IIR(3));
>  		if (tmp) {
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 0eff337..ca4f8b9 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4194,6 +4194,7 @@ enum punit_power_well {
>  #define  GEN8_DE_PIPE_A_IRQ		(1<<16)
>  #define  GEN8_DE_PIPE_IRQ(pipe)		(1<<(16+pipe))
>  #define  GEN8_GT_VECS_IRQ		(1<<6)
> +#define  GEN8_GT_PM_IRQ			(1<<4)
>  #define  GEN8_GT_VCS2_IRQ		(1<<3)
>  #define  GEN8_GT_VCS1_IRQ		(1<<2)
>  #define  GEN8_GT_BCS_IRQ		(1<<1)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index d8b540b..d560a9b 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -653,6 +653,8 @@ void ilk_enable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask);
>  void ilk_disable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask);
>  void snb_enable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
>  void snb_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> +void bdw_enable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> +void bdw_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
>  void intel_runtime_pm_disable_interrupts(struct drm_device *dev);
>  void intel_runtime_pm_restore_interrupts(struct drm_device *dev);
>  int intel_get_crtc_scanline(struct intel_crtc *crtc);
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 834c49c..0e69c97 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3246,6 +3246,26 @@ void valleyview_set_rps(struct drm_device *dev, u8 val)
>  	trace_intel_gpu_freq_change(vlv_gpu_freq(dev_priv, val));
>  }
>  
> +static void gen8_disable_rps_interrupts(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +
> +	I915_WRITE(GEN6_PMINTRMSK, 0xffffffff);
> +	I915_WRITE(GEN8_GT_IER(2), I915_READ(GEN8_GT_IER(2)) &
> +				   ~dev_priv->pm_rps_events);
> +	/* Complete PM interrupt masking here doesn't race with the rps work
> +	 * item again unmasking PM interrupts because that is using a different
> +	 * register (GEN8_GT_IMR(2)) to mask PM interrupts. The only risk is in
> +	 * leaving stale bits in GEN8_GT_IIR(2) and GEN8_GT_IMR(2) which
> +	 * gen8_enable_rps will clean up. */
> +
> +	spin_lock_irq(&dev_priv->irq_lock);
> +	dev_priv->rps.pm_iir = 0;
> +	spin_unlock_irq(&dev_priv->irq_lock);
> +
> +	I915_WRITE(GEN8_GT_IIR(2), dev_priv->pm_rps_events);
> +}
> +
>  static void gen6_disable_rps_interrupts(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -3272,7 +3292,10 @@ static void gen6_disable_rps(struct drm_device *dev)
>  	I915_WRITE(GEN6_RC_CONTROL, 0);
>  	I915_WRITE(GEN6_RPNSWREQ, 1 << 31);
>  
> -	gen6_disable_rps_interrupts(dev);
> +	if (IS_BROADWELL(dev))
> +		gen8_disable_rps_interrupts(dev);
> +	else
> +		gen6_disable_rps_interrupts(dev);
>  }
>  
>  static void valleyview_disable_rps(struct drm_device *dev)
> @@ -3344,6 +3367,17 @@ int intel_enable_rc6(const struct drm_device *dev)
>  	return i915.enable_rc6;
>  }
>  
> +static void gen8_enable_rps_interrupts(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +
> +	spin_lock_irq(&dev_priv->irq_lock);
> +	WARN_ON(dev_priv->rps.pm_iir);
> +	bdw_enable_pm_irq(dev_priv, dev_priv->pm_rps_events);
> +	I915_WRITE(GEN8_GT_IIR(2), dev_priv->pm_rps_events);
> +	spin_unlock_irq(&dev_priv->irq_lock);
> +}
> +
>  static void gen6_enable_rps_interrupts(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -3446,7 +3480,7 @@ static void gen8_enable_rps(struct drm_device *dev)
>  
>  	gen6_set_rps(dev, (I915_READ(GEN6_GT_PERF_STATUS) & 0xff00) >> 8);
>  
> -	gen6_enable_rps_interrupts(dev);
> +	gen8_enable_rps_interrupts(dev);
>  
>  	gen6_gt_force_wake_put(dev_priv, FORCEWAKE_ALL);
>  }
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC