Re: [PATCH v7 1/3] drm/i915: Replaced Blitter ring based flips with MMIO flips

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

On Thu, May 22, 2014 at 08:06:31PM +0530, sourab.gupta@intel.com wrote:
> From: Sourab Gupta <sourab.gupta@intel.com>
> 
> Using MMIO based flips on Gen5+. The MMIO flips are useful for the Media power
> well residency optimization. These maybe enabled on architectures where
> Render and Blitter engines reside in different power wells.
> The blitter ring is currently being used just for command streamer based
> flip calls. For pure 3D workloads in such cases, 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
> 
> v4: Addressing Ville's review comments
>     -general cleanup
>     -updating only base addr instead of calling update_primary_plane
>     -extending patch for gen5+ platforms
> 
> v5: Addressed Ville's review comments
>     -Making mmio flip vs cs flip selection based on module parameter
>     -Adding check for DRIVER_MODESET feature in notify_ring before calling
>      notify mmio flip.
>     -Other changes mostly in function arguments
> 
> v6: -Having a seperate function to check condition for using mmio flips (Ville)
>     -propogating error code from i915_gem_check_olr (Ville)
> 
> v7: -Adding __must_check with i915_gem_check_olr (Chris)
>     -Renaming mmio_flip_data to mmio_flip (Chris)
>     -Rebasing on latest nightly
> 
> Signed-off-by: Sourab Gupta <sourab.gupta@intel.com>
> Signed-off-by: Akash Goel <akash.goel@intel.com>

Seems the mmio vs cs flip race patches landed finally, so this needs a
rebase to kill the pin stuff from intel_queue_mmio_flip(), and that
also means you can squash patch 3/3 with this one. Also needs a
s/ring_buffer/engine_cs/ since that stuff also got changed.

Oh and Chris was right about the tiling thing. I totally forgot about
that when I said you shouldn't use .update_primary_plane(). I think
the easiest solution would be to stick the new tiling mode into the
mmio flip data, and just update DSPCNTR with a RMW in the flip notify
function. IIIRC we already have test for tiling change during page
flip in igt.

> ---
>  drivers/gpu/drm/i915/i915_dma.c      |   1 +
>  drivers/gpu/drm/i915/i915_drv.h      |   7 ++
>  drivers/gpu/drm/i915/i915_gem.c      |   2 +-
>  drivers/gpu/drm/i915/i915_irq.c      |   3 +
>  drivers/gpu/drm/i915/i915_params.c   |   4 ++
>  drivers/gpu/drm/i915/intel_display.c | 133 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h     |   6 ++
>  7 files changed, 155 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 20df7c72..266c9a6 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1571,6 +1571,7 @@ 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 13495a4..ced6e58 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1366,6 +1366,9 @@ struct drm_i915_private {
>  	/* protects the irq masks */
>  	spinlock_t irq_lock;
>  
> +	/* protects the mmio flip data */
> +	spinlock_t mmio_flip_lock;
> +
>  	bool display_irqs_enabled;
>  
>  	/* To control wakeup latency, e.g. for irq-driven dp aux transfers. */
> @@ -2036,6 +2039,7 @@ struct i915_params {
>  	bool reset;
>  	bool disable_display;
>  	bool disable_vtd_wa;
> +	bool use_mmio_flip;
>  };
>  extern struct i915_params i915 __read_mostly;
>  
> @@ -2230,6 +2234,7 @@ bool i915_gem_retire_requests(struct drm_device *dev);
>  void i915_gem_retire_requests_ring(struct intel_ring_buffer *ring);
>  int __must_check i915_gem_check_wedge(struct i915_gpu_error *error,
>  				      bool interruptible);
> +int __must_check i915_gem_check_olr(struct intel_ring_buffer *ring, u32 seqno);
>  static inline bool i915_reset_in_progress(struct i915_gpu_error *error)
>  {
>  	return unlikely(atomic_read(&error->reset_counter)
> @@ -2598,6 +2603,8 @@ 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 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_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index f2713b9..bc6fe4e 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1096,7 +1096,7 @@ i915_gem_check_wedge(struct i915_gpu_error *error,
>   * Compare seqno against outstanding lazy request. Emit a request if they are
>   * equal.
>   */
> -static int
> +__must_check int
>  i915_gem_check_olr(struct intel_ring_buffer *ring, u32 seqno)
>  {
>  	int ret;
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 2043276..f244b23 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1155,6 +1155,9 @@ static void notify_ring(struct drm_device *dev,
>  
>  	trace_i915_gem_request_complete(ring);
>  
> +	if (drm_core_check_feature(dev, DRIVER_MODESET))
> +		intel_notify_mmio_flip(ring);
> +
>  	wake_up_all(&ring->irq_queue);
>  	i915_queue_hangcheck(dev);
>  }
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index d05a2af..e0d44df 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -48,6 +48,7 @@ struct i915_params i915 __read_mostly = {
>  	.disable_display = 0,
>  	.enable_cmd_parser = 1,
>  	.disable_vtd_wa = 0,
> +	.use_mmio_flip = 0,
>  };
>  
>  module_param_named(modeset, i915.modeset, int, 0400);
> @@ -156,3 +157,6 @@ MODULE_PARM_DESC(disable_vtd_wa, "Disable all VT-d workarounds (default: false)"
>  module_param_named(enable_cmd_parser, i915.enable_cmd_parser, int, 0600);
>  MODULE_PARM_DESC(enable_cmd_parser,
>  		 "Enable command parsing (1=enabled [default], 0=disabled)");
> +
> +module_param_named(use_mmio_flip, i915.use_mmio_flip, bool, 0600);
> +MODULE_PARM_DESC(use_mmio_flip, "use MMIO flips (default: false)");
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 19b92c1..a29552d 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9179,6 +9179,136 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
>  	return 0;
>  }
>  
> +static bool intel_use_mmio_flip(struct drm_device *dev)
> +{
> +	/* If module parameter is disabled, use CS flips.
> +	 * Otherwise, use MMIO flips starting from Gen5.
> +	 * This is not being used for older platforms, because
> +	 * non-availability of flip done interrupt forces us to use
> +	 * CS flips. Older platforms derive flip done using some clever
> +	 * tricks involving the flip_pending status bits and vblank irqs.
> +	 * So using MMIO flips there would disrupt this mechanism.
> +	 */
> +
> +	if (i915.use_mmio_flip == 0)
> +		return false;
> +
> +	if (INTEL_INFO(dev)->gen >= 5)
> +		return true;
> +	else
> +		return false;
> +}
> +
> +static void intel_do_mmio_flip(struct intel_crtc *intel_crtc)
> +{
> +	struct drm_i915_private *dev_priv =
> +		intel_crtc->base.dev->dev_private;
> +	struct intel_framebuffer *intel_fb =
> +		to_intel_framebuffer(intel_crtc->base.primary->fb);
> +	struct drm_i915_gem_object *obj = intel_fb->obj;
> +
> +	intel_mark_page_flip_active(intel_crtc);
> +
> +	I915_WRITE(DSPSURF(intel_crtc->plane), i915_gem_obj_ggtt_offset(obj) +
> +			intel_crtc->dspaddr_offset);
> +	POSTING_READ(DSPSURF(intel_crtc->plane));
> +}
> +
> +static int intel_postpone_flip(struct drm_i915_gem_object *obj)
> +{
> +	int ret;
> +
> +	if (!obj->ring)
> +		return 0;
> +
> +	if (i915_seqno_passed(obj->ring->get_seqno(obj->ring, true),
> +				obj->last_write_seqno))
> +		return 0;
> +
> +	ret = i915_gem_check_olr(obj->ring, obj->last_write_seqno);
> +	if (ret)
> +		return ret;
> +
> +	if (WARN_ON(!obj->ring->irq_get(obj->ring)))
> +		return 0;
> +
> +	return 1;
> +}
> +
> +void intel_notify_mmio_flip(struct intel_ring_buffer *ring)
> +{
> +	struct drm_i915_private *dev_priv = ring->dev->dev_private;
> +	struct intel_crtc *intel_crtc;
> +	unsigned long irq_flags;
> +	u32 seqno;
> +
> +	seqno = ring->get_seqno(ring, false);
> +
> +	spin_lock_irqsave(&dev_priv->mmio_flip_lock, irq_flags);
> +	for_each_intel_crtc(ring->dev, intel_crtc) {
> +		struct intel_mmio_flip *mmio_flip;
> +
> +		mmio_flip = &intel_crtc->mmio_flip;
> +
> +		if (mmio_flip->seqno == 0)
> +			continue;
> +		if (ring->id != mmio_flip->ring_id)
> +			continue;
> +
> +		if (i915_seqno_passed(seqno, mmio_flip->seqno)) {
> +			intel_do_mmio_flip(intel_crtc);
> +			mmio_flip->seqno = 0;
> +			ring->irq_put(ring);
> +		}
> +	}
> +	spin_unlock_irqrestore(&dev_priv->mmio_flip_lock, irq_flags);
> +}
> +
> +static int intel_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;
> +
> +	if (WARN_ON(intel_crtc->mmio_flip.seqno)) {
> +		ret = -EBUSY;
> +		goto err_unpin;
> +	}
> +
> +	ret = intel_postpone_flip(obj);
> +	if (ret < 0) {
> +		goto err_unpin;
> +	} else if (ret == 0) {
> +		intel_do_mmio_flip(intel_crtc);
> +		return 0;
> +	}
> +
> +	spin_lock_irqsave(&dev_priv->mmio_flip_lock, irq_flags);
> +	intel_crtc->mmio_flip.seqno = obj->last_write_seqno;
> +	intel_crtc->mmio_flip.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(obj->ring);
> +	return 0;
> +
> +err_unpin:
> +	intel_unpin_fb_obj(obj);
> +err:
> +	return ret;
> +}
> +
>  static int intel_default_queue_flip(struct drm_device *dev,
>  				    struct drm_crtc *crtc,
>  				    struct drm_framebuffer *fb,
> @@ -11470,6 +11600,9 @@ static void intel_init_display(struct drm_device *dev)
>  		break;
>  	}
>  
> +	if (intel_use_mmio_flip(dev))
> +		dev_priv->display.queue_flip = intel_queue_mmio_flip;
> +
>  	intel_panel_init_backlight_funcs(dev);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 287b89e..5a4f60c 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -358,6 +358,11 @@ struct intel_pipe_wm {
>  	bool sprites_scaled;
>  };
>  
> +struct intel_mmio_flip {
> +	u32 seqno;
> +	u32 ring_id;
> +};
> +
>  struct intel_crtc {
>  	struct drm_crtc base;
>  	enum pipe pipe;
> @@ -409,6 +414,7 @@ struct intel_crtc {
>  	} wm;
>  
>  	wait_queue_head_t vbl_wait;
> +	struct intel_mmio_flip mmio_flip;
>  };
>  
>  struct intel_plane_wm_parameters {
> -- 
> 1.8.5.1

-- 
Ville Syrjälä
Intel OTC