Re: [PATCH 23/43] drm/i915/bdw: Interrupts with logical rings

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Jul 24, 2014 at 05:04:31PM +0100, Thomas Daniel wrote:
> From: Oscar Mateo <oscar.mateo@intel.com>
> 
> We need to attend context switch interrupts from all rings. Also, fixed writing
> IMR/IER and added HWSTAM at ring init time.
> 
> Notice that, if added to irq_enable_mask, the context switch interrupts would
> be incorrectly masked out when the user interrupts are due to no users waiting
> on a sequence number. Therefore, this commit adds a bitmask of interrupts to
> be kept unmasked at all times.
> 
> v2: Disable HWSTAM, as suggested by Damien (nobody listens to these interrupts,
> anyway).
> 
> v3: Add new get/put_irq functions.
> 
> Signed-off-by: Thomas Daniel <thomas.daniel@intel.com> (v1)
> Signed-off-by: Oscar Mateo <oscar.mateo@intel.com> (v2 & v3)

irq_keep_mask is a nifty idea, would be pretty to roll it out for legacy
rings too. But totally optional.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_irq.c         |   19 ++++++++--
>  drivers/gpu/drm/i915/i915_reg.h         |    3 ++
>  drivers/gpu/drm/i915/intel_lrc.c        |   58 +++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_ringbuffer.h |    1 +
>  4 files changed, 78 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index a38b5c3..f77a4ca 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1643,6 +1643,8 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
>  				notify_ring(dev, &dev_priv->ring[RCS]);
>  			if (bcs & GT_RENDER_USER_INTERRUPT)
>  				notify_ring(dev, &dev_priv->ring[BCS]);
> +			if ((rcs | bcs) & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
> +				DRM_DEBUG_DRIVER("TODO: Context switch\n");
>  		} else
>  			DRM_ERROR("The master control interrupt lied (GT0)!\n");
>  	}
> @@ -1655,9 +1657,13 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
>  			vcs = tmp >> GEN8_VCS1_IRQ_SHIFT;
>  			if (vcs & GT_RENDER_USER_INTERRUPT)
>  				notify_ring(dev, &dev_priv->ring[VCS]);
> +			if (vcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
> +				DRM_DEBUG_DRIVER("TODO: Context switch\n");
>  			vcs = tmp >> GEN8_VCS2_IRQ_SHIFT;
>  			if (vcs & GT_RENDER_USER_INTERRUPT)
>  				notify_ring(dev, &dev_priv->ring[VCS2]);
> +			if (vcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
> +				DRM_DEBUG_DRIVER("TODO: Context switch\n");
>  		} else
>  			DRM_ERROR("The master control interrupt lied (GT1)!\n");
>  	}
> @@ -1681,6 +1687,8 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
>  			vcs = tmp >> GEN8_VECS_IRQ_SHIFT;
>  			if (vcs & GT_RENDER_USER_INTERRUPT)
>  				notify_ring(dev, &dev_priv->ring[VECS]);
> +			if (vcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
> +				DRM_DEBUG_DRIVER("TODO: Context switch\n");
>  		} else
>  			DRM_ERROR("The master control interrupt lied (GT3)!\n");
>  	}
> @@ -3768,12 +3776,17 @@ static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
>  	/* These are interrupts we'll toggle with the ring mask register */
>  	uint32_t gt_interrupts[] = {
>  		GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
> +			GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
>  			GT_RENDER_L3_PARITY_ERROR_INTERRUPT |
> -			GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT,
> +			GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT |
> +			GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT,
>  		GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
> -			GT_RENDER_USER_INTERRUPT << GEN8_VCS2_IRQ_SHIFT,
> +			GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
> +			GT_RENDER_USER_INTERRUPT << GEN8_VCS2_IRQ_SHIFT |
> +			GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS2_IRQ_SHIFT,
>  		0,
> -		GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT
> +		GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT |
> +			GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT
>  		};
>  
>  	for (i = 0; i < ARRAY_SIZE(gt_interrupts); i++)
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 70dddac..bfc0c01 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1062,6 +1062,7 @@ enum punit_power_well {
>  #define RING_ACTHD_UDW(base)	((base)+0x5c)
>  #define RING_NOPID(base)	((base)+0x94)
>  #define RING_IMR(base)		((base)+0xa8)
> +#define RING_HWSTAM(base)	((base)+0x98)
>  #define RING_TIMESTAMP(base)	((base)+0x358)
>  #define   TAIL_ADDR		0x001FFFF8
>  #define   HEAD_WRAP_COUNT	0xFFE00000
> @@ -4590,6 +4591,8 @@ enum punit_power_well {
>  #define GEN8_GT_IIR(which) (0x44308 + (0x10 * (which)))
>  #define GEN8_GT_IER(which) (0x4430c + (0x10 * (which)))
>  
> +#define GEN8_GT_CONTEXT_SWITCH_INTERRUPT	(1 <<  8)
> +
>  #define GEN8_BCS_IRQ_SHIFT 16
>  #define GEN8_RCS_IRQ_SHIFT 0
>  #define GEN8_VCS2_IRQ_SHIFT 16
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index c30518c..a6dcb3a 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -343,6 +343,9 @@ static int gen8_init_common_ring(struct intel_engine_cs *ring)
>  	struct drm_device *dev = ring->dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
> +	I915_WRITE_IMR(ring, ~(ring->irq_enable_mask | ring->irq_keep_mask));
> +	I915_WRITE(RING_HWSTAM(ring->mmio_base), 0xffffffff);
> +
>  	I915_WRITE(RING_MODE_GEN7(ring),
>  		_MASKED_BIT_DISABLE(GFX_REPLAY_MODE) |
>  		_MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE));
> @@ -381,6 +384,39 @@ static int gen8_init_render_ring(struct intel_engine_cs *ring)
>  	return ret;
>  }
>  
> +static bool gen8_logical_ring_get_irq(struct intel_engine_cs *ring)
> +{
> +	struct drm_device *dev = ring->dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	unsigned long flags;
> +
> +	if (!dev->irq_enabled)
> +		return false;
> +
> +	spin_lock_irqsave(&dev_priv->irq_lock, flags);
> +	if (ring->irq_refcount++ == 0) {
> +		I915_WRITE_IMR(ring, ~(ring->irq_enable_mask | ring->irq_keep_mask));
> +		POSTING_READ(RING_IMR(ring->mmio_base));
> +	}
> +	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
> +
> +	return true;
> +}
> +
> +static void gen8_logical_ring_put_irq(struct intel_engine_cs *ring)
> +{
> +	struct drm_device *dev = ring->dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev_priv->irq_lock, flags);
> +	if (--ring->irq_refcount == 0) {
> +		I915_WRITE_IMR(ring, ~ring->irq_keep_mask);
> +		POSTING_READ(RING_IMR(ring->mmio_base));
> +	}
> +	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
> +}
> +
>  static int gen8_emit_flush(struct intel_ringbuffer *ringbuf,
>  			   u32 invalidate_domains,
>  			   u32 unused)
> @@ -566,6 +602,10 @@ static int logical_render_ring_init(struct drm_device *dev)
>  	ring->mmio_base = RENDER_RING_BASE;
>  	ring->irq_enable_mask =
>  		GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT;
> +	ring->irq_keep_mask =
> +		GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT;
> +	if (HAS_L3_DPF(dev))
> +		ring->irq_keep_mask |= GT_RENDER_L3_PARITY_ERROR_INTERRUPT;
>  
>  	ring->init = gen8_init_render_ring;
>  	ring->cleanup = intel_fini_pipe_control;
> @@ -573,6 +613,8 @@ static int logical_render_ring_init(struct drm_device *dev)
>  	ring->set_seqno = gen8_set_seqno;
>  	ring->emit_request = gen8_emit_request;
>  	ring->emit_flush = gen8_emit_flush_render;
> +	ring->irq_get = gen8_logical_ring_get_irq;
> +	ring->irq_put = gen8_logical_ring_put_irq;
>  
>  	return logical_ring_init(dev, ring);
>  }
> @@ -587,12 +629,16 @@ static int logical_bsd_ring_init(struct drm_device *dev)
>  	ring->mmio_base = GEN6_BSD_RING_BASE;
>  	ring->irq_enable_mask =
>  		GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT;
> +	ring->irq_keep_mask =
> +		GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT;
>  
>  	ring->init = gen8_init_common_ring;
>  	ring->get_seqno = gen8_get_seqno;
>  	ring->set_seqno = gen8_set_seqno;
>  	ring->emit_request = gen8_emit_request;
>  	ring->emit_flush = gen8_emit_flush;
> +	ring->irq_get = gen8_logical_ring_get_irq;
> +	ring->irq_put = gen8_logical_ring_put_irq;
>  
>  	return logical_ring_init(dev, ring);
>  }
> @@ -607,12 +653,16 @@ static int logical_bsd2_ring_init(struct drm_device *dev)
>  	ring->mmio_base = GEN8_BSD2_RING_BASE;
>  	ring->irq_enable_mask =
>  		GT_RENDER_USER_INTERRUPT << GEN8_VCS2_IRQ_SHIFT;
> +	ring->irq_keep_mask =
> +		GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS2_IRQ_SHIFT;
>  
>  	ring->init = gen8_init_common_ring;
>  	ring->get_seqno = gen8_get_seqno;
>  	ring->set_seqno = gen8_set_seqno;
>  	ring->emit_request = gen8_emit_request;
>  	ring->emit_flush = gen8_emit_flush;
> +	ring->irq_get = gen8_logical_ring_get_irq;
> +	ring->irq_put = gen8_logical_ring_put_irq;
>  
>  	return logical_ring_init(dev, ring);
>  }
> @@ -627,12 +677,16 @@ static int logical_blt_ring_init(struct drm_device *dev)
>  	ring->mmio_base = BLT_RING_BASE;
>  	ring->irq_enable_mask =
>  		GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT;
> +	ring->irq_keep_mask =
> +		GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT;
>  
>  	ring->init = gen8_init_common_ring;
>  	ring->get_seqno = gen8_get_seqno;
>  	ring->set_seqno = gen8_set_seqno;
>  	ring->emit_request = gen8_emit_request;
>  	ring->emit_flush = gen8_emit_flush;
> +	ring->irq_get = gen8_logical_ring_get_irq;
> +	ring->irq_put = gen8_logical_ring_put_irq;
>  
>  	return logical_ring_init(dev, ring);
>  }
> @@ -647,12 +701,16 @@ static int logical_vebox_ring_init(struct drm_device *dev)
>  	ring->mmio_base = VEBOX_RING_BASE;
>  	ring->irq_enable_mask =
>  		GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT;
> +	ring->irq_keep_mask =
> +		GEN8_GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT;
>  
>  	ring->init = gen8_init_common_ring;
>  	ring->get_seqno = gen8_get_seqno;
>  	ring->set_seqno = gen8_set_seqno;
>  	ring->emit_request = gen8_emit_request;
>  	ring->emit_flush = gen8_emit_flush;
> +	ring->irq_get = gen8_logical_ring_get_irq;
> +	ring->irq_put = gen8_logical_ring_put_irq;
>  
>  	return logical_ring_init(dev, ring);
>  }
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 6e22866..09102b2 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -223,6 +223,7 @@ struct  intel_engine_cs {
>  	} semaphore;
>  
>  	/* Execlists */
> +	u32             irq_keep_mask; /* bitmask for interrupts that should not be masked */
>  	int		(*emit_request)(struct intel_ringbuffer *ringbuf);
>  	int		(*emit_flush)(struct intel_ringbuffer *ringbuf,
>  				      u32 invalidate_domains,
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch