Re: [PATCH v3] drm/i915: Replaced Blitter ring based flips with MMIO flips for VLV

["Gupta, Sourab" <sourab.gupta@intel.com>]

Hi Ville/Damien,
Can you please review the below patch(v3) for mmio flips.
Thanks,
Sourab

On Sun, 2014-03-23 at 09:01 +0000, Gupta, Sourab wrote:
> From: Sourab Gupta <sourab.gupta@intel.com>
> 
> Using MMIO based flips on VLV for Media power well residency optimization.
> The blitter ring is currently being used just for command streamer based
> flip calls. For pure 3D workloads, with MMIO flips, there will be no use
> of blitter ring and this will ensure the 100% residency for Media well.
> 
> v2: The MMIO flips now use the interrupt driven mechanism for issuing the
> flips when target seqno is reached. (Incorporating Ville's idea)
> 
> v3: Rebasing on latest code. Code restructuring after incorporating
> Damien's comments
> 
> Signed-off-by: Sourab Gupta <sourab.gupta@intel.com>
> Signed-off-by: Akash Goel <akash.goel@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c      |   1 +
>  drivers/gpu/drm/i915/i915_drv.h      |   7 ++
>  drivers/gpu/drm/i915/i915_irq.c      |   2 +
>  drivers/gpu/drm/i915/intel_display.c | 124 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h     |   7 ++
>  5 files changed, 141 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 4e0a26a..bca3c5a 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1569,6 +1569,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>  	spin_lock_init(&dev_priv->backlight_lock);
>  	spin_lock_init(&dev_priv->uncore.lock);
>  	spin_lock_init(&dev_priv->mm.object_stat_lock);
> +	spin_lock_init(&dev_priv->mmio_flip_lock);
>  	mutex_init(&dev_priv->dpio_lock);
>  	mutex_init(&dev_priv->modeset_restore_lock);
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 3f62be0..678d31d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1621,6 +1621,10 @@ typedef struct drm_i915_private {
>  	struct i915_dri1_state dri1;
>  	/* Old ums support infrastructure, same warning applies. */
>  	struct i915_ums_state ums;
> +
> +	/* protects the mmio flip data */
> +	spinlock_t mmio_flip_lock;
> +
>  } drm_i915_private_t;
>  
>  static inline struct drm_i915_private *to_i915(const struct drm_device *dev)
> @@ -2657,6 +2661,9 @@ int i915_reg_read_ioctl(struct drm_device *dev, void *data,
>  int i915_get_reset_stats_ioctl(struct drm_device *dev, void *data,
>  			       struct drm_file *file);
>  
> +void intel_notify_mmio_flip(struct drm_device *dev,
> +			struct intel_ring_buffer *ring);
> +
>  /* overlay */
>  extern struct intel_overlay_error_state *intel_overlay_capture_error_state(struct drm_device *dev);
>  extern void intel_overlay_print_error_state(struct drm_i915_error_state_buf *e,
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 4b4aeb3..ad26abe 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1080,6 +1080,8 @@ static void notify_ring(struct drm_device *dev,
>  
>  	trace_i915_gem_request_complete(ring);
>  
> +	intel_notify_mmio_flip(dev, ring);
> +
>  	wake_up_all(&ring->irq_queue);
>  	i915_queue_hangcheck(dev);
>  }
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7e4ea8d..19004bf 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -8782,6 +8782,125 @@ err:
>  	return ret;
>  }
>  
> +static int intel_do_mmio_flip(struct drm_device *dev,
> +			struct drm_crtc *crtc)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct intel_crtc *intel_crtc;
> +
> +	intel_crtc = to_intel_crtc(crtc);
> +
> +	intel_mark_page_flip_active(intel_crtc);
> +	return dev_priv->display.update_primary_plane(crtc, crtc->fb, 0, 0);
> +}
> +
> +static bool intel_postpone_flip(struct drm_i915_gem_object *obj)
> +{
> +	int ret;
> +	if (!obj->ring)
> +		return false;
> +
> +	if (i915_seqno_passed(obj->ring->get_seqno(obj->ring, false),
> +			      obj->last_write_seqno))
> +		return false;
> +
> +	if (obj->last_write_seqno == obj->ring->outstanding_lazy_seqno) {
> +		ret = i915_add_request(obj->ring, NULL);
> +		if (WARN_ON(ret))
> +			return false;
> +	}
> +
> +	if (WARN_ON(!obj->ring->irq_get(obj->ring)))
> +		return false;
> +
> +	return true;
> +}
> +
> +void intel_notify_mmio_flip(struct drm_device *dev,
> +			struct intel_ring_buffer *ring)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct drm_crtc *crtc;
> +	struct intel_crtc *intel_crtc;
> +	struct intel_mmio_flip *mmio_flip_data;
> +	unsigned long irq_flags;
> +	u32 seqno;
> +	enum pipe pipe;
> +
> +	BUG_ON(!ring);
> +
> +	seqno = ring->get_seqno(ring, false);
> +
> +	spin_lock_irqsave(&dev_priv->mmio_flip_lock, irq_flags);
> +	for_each_pipe(pipe) {
> +		crtc = dev_priv->pipe_to_crtc_mapping[pipe];
> +		intel_crtc = to_intel_crtc(crtc);
> +		mmio_flip_data = &intel_crtc->mmio_flip_data;
> +		if ((mmio_flip_data->seqno != 0) &&
> +				(ring->id == mmio_flip_data->ring_id) &&
> +				(seqno >= mmio_flip_data->seqno)) {
> +			intel_do_mmio_flip(dev, crtc);
> +			mmio_flip_data->seqno = 0;
> +			ring->irq_put(ring);
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dev_priv->mmio_flip_lock, irq_flags);
> +}
> +
> +/* Using MMIO based flips starting from VLV, for Media power well
> + * residency optimization. The other alternative of having Render
> + * ring based flip calls is not being used, as the performance
> + * (FPS) of certain 3D Apps was getting severly affected.
> + */
> +static int intel_gen7_queue_mmio_flip(struct drm_device *dev,
> +			struct drm_crtc *crtc,
> +			struct drm_framebuffer *fb,
> +			struct drm_i915_gem_object *obj,
> +			uint32_t flags)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> +	unsigned long irq_flags;
> +	int ret;
> +
> +	ret = intel_pin_and_fence_fb_obj(dev, obj, obj->ring);
> +	if (ret)
> +		goto err;
> +
> +	switch (intel_crtc->plane) {
> +	case PLANE_A:
> +	case PLANE_B:
> +	case PLANE_C:
> +	break;
> +	default:
> +		WARN_ONCE(1, "unknown plane in flip command\n");
> +		ret = -ENODEV;
> +		goto err_unpin;
> +	}
> +
> +	if (!intel_postpone_flip(obj)) {
> +		ret = intel_do_mmio_flip(dev, crtc);
> +		return ret;
> +	}
> +
> +	spin_lock_irqsave(&dev_priv->mmio_flip_lock, irq_flags);
> +	intel_crtc->mmio_flip_data.seqno = obj->last_write_seqno;
> +	intel_crtc->mmio_flip_data.ring_id = obj->ring->id;
> +	spin_unlock_irqrestore(&dev_priv->mmio_flip_lock, irq_flags);
> +
> +	/* Double check to catch cases where irq fired before
> +	 * mmio flip data was ready
> +	 */
> +	intel_notify_mmio_flip(dev, obj->ring);
> +	return 0;
> +
> +err_unpin:
> +	intel_unpin_fb_obj(obj);
> +err:
> +	return ret;
> +}
> +
>  static int intel_gen7_queue_flip(struct drm_device *dev,
>  				 struct drm_crtc *crtc,
>  				 struct drm_framebuffer *fb,
> @@ -10577,6 +10696,8 @@ static void intel_crtc_init(struct drm_device *dev, int pipe)
>  		DRM_DEBUG_KMS("swapping pipes & planes for FBC\n");
>  		intel_crtc->plane = !pipe;
>  	}
> +	if (IS_VALLEYVIEW(dev))
> +			intel_crtc->mmio_flip_data.seqno = 0;
>  
>  	BUG_ON(pipe >= ARRAY_SIZE(dev_priv->plane_to_crtc_mapping) ||
>  	       dev_priv->plane_to_crtc_mapping[intel_crtc->plane] != NULL);
> @@ -11107,6 +11228,9 @@ static void intel_init_display(struct drm_device *dev)
>  	}
>  
>  	intel_panel_init_backlight_funcs(dev);
> +
> +	if (IS_VALLEYVIEW(dev))
> +		dev_priv->display.queue_flip = intel_gen7_queue_mmio_flip;
>  }
>  
>  /*
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index fa99104..f0b26a1 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -344,6 +344,11 @@ struct intel_pipe_wm {
>  	bool fbc_wm_enabled;
>  };
>  
> +struct intel_mmio_flip {
> +	u32 seqno;
> +	u32 ring_id;
> +};
> +
>  struct intel_crtc {
>  	struct drm_crtc base;
>  	enum pipe pipe;
> @@ -395,6 +400,8 @@ struct intel_crtc {
>  		/* watermarks currently being used  */
>  		struct intel_pipe_wm active;
>  	} wm;
> +
> +	struct intel_mmio_flip	mmio_flip_data;
>  };
>  
>  struct intel_plane_wm_parameters {