[Intel-gfx] [PATCH] i915: support page flipping

Jesse Barnes jbarnes at virtuousgeek.org
Thu Feb 26 23:35:39 CET 2009


On Thursday, February 26, 2009 1:56:52 pm Chris Wilson wrote:
> On Thu, 2009-02-26 at 13:28 -0800, Jesse Barnes wrote:
> > Add a new page flip ioctl to the i915 driver.  The new ioctl takes the
> > new drm_i915_gem_page_flip arg, which contains a buffer object target for
> > the flip, an offset into that buffer, and other buffer parameters to be
> > used for the flip.
> >
> > If a flip is already pending on the object in question, the ioctl waits
> > for it to finish first, then queues the flip.  An optional wait flag
> > causes the ioctl to wait for the flip to complete before the it returns.
> >
> > If an execbuffer containing an object with a pending flip comes in, it
> > will stall until the flip completes, to preserve glXSwapBuffers
> > semantics.
> >
> > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
>
> Didn't do too bad in spotting the missing checks... ;-)

... but I just had to leave a few nuggets for you. :)

> This has annoyed me every time (but I'm running out of things I can
> complain about ;-), can we just say
>   pending = !list_empty();
> and be done with the conditional.

Sure, fixed.

> > +	obj_priv = obj->driver_private;
>
> Need to check obj_priv->stride&7 == 0. Hmm, that may be impossible
> anyway.

I've left that out, though I guess it wouldn't hurt.

> > +	vblank_ref_err = drm_vblank_get(dev, pipe);
> > +	if (!vblank_ref_err) {
>
> Ok, this seems like a reasonable fallback. If vblank is not enabled then
> you just queue the flip without waiting.

Right, but I also forgot to unref in the pin failure case, so I've fixed that.

> > +		ret = i915_gem_object_pin(obj, 0);
> > +		if (ret) {
> > +			DRM_ERROR("failed to pin object for flip\n");
> > +			ret = -EBUSY;
>
> What's the rationale for changing the reported error here? (And it might
> be helpful to printk the original error value.)

Oh I'm not sure what's going on there; I've changed it to just return the pin
failure.

> > +	 * Put the object in the GTT domain before the flip,
> > +	 * since there may be outstanding rendering
> > +	 */
> > +	i915_gem_object_set_to_gtt_domain(obj, 0);
>
> Need to check, report and handle errors here. And yes, these do occur in
> the wild for some as of yet unknown reason.

Fixed.  Though Mesa is now flushing before calling the server so it should
happen less often.

> > +	reqno = i915_add_request(dev, 0);
>
> Be consistent and call this seqno like the rest of the code, please.

Sure, fixed.

> > +	/* Look up object handles */
> > +	for (i = 0; i < args->buffer_count; i++) {
> > +		object_list[i] = drm_gem_object_lookup(dev, file_priv,
> > +						       exec_list[i].handle);
> > +		if (object_list[i] == NULL) {
> > +			DRM_ERROR("Invalid object handle %d at index %d\n",
> > +				   exec_list[i].handle, i);
> > +			ret = -EBADF;
> > +			goto pre_mutex_err;
>
> Hmm, can't jump straight to pre_mutex_err as that means you leak the
> references on object already looked up. Take the mutex and goto err;

Ah yeah, missed that, looks like 'i' will be right if we jump there too;
fixed.

-- 
Jesse Barnes, Intel Open Source Technology Center

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 2d797ff..050682a 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -829,6 +829,178 @@ static int i915_set_status_page(struct drm_device *dev, void *data,
 	return 0;
 }
 
+static int i915_pipe_to_plane(struct drm_device *dev, int pipe)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	u32 reg, pipe_mask;
+
+	if (pipe == 0)
+		pipe_mask = DISPPLANE_SEL_PIPE_A;
+	else
+		pipe_mask = DISPPLANE_SEL_PIPE_B;
+
+	pipe_mask |= DISPLAY_PLANE_ENABLE;
+
+	reg = I915_READ(DSPACNTR);
+	if ((reg & (DISPLAY_PLANE_ENABLE | DISPPLANE_SEL_PIPE_MASK)) ==
+	    pipe_mask)
+		return 0;
+
+	reg = I915_READ(DSPBCNTR);
+	if ((reg & (DISPLAY_PLANE_ENABLE | DISPPLANE_SEL_PIPE_MASK)) ==
+	    pipe_mask)
+		return 1;
+
+	return -1;
+}
+
+bool
+i915_gem_flip_pending(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj_priv = obj->driver_private;
+	unsigned long flags;
+	bool pending;
+
+	spin_lock_irqsave(&dev_priv->vblank_lock, flags);
+	pending = !list_empty(&obj_priv->vblank_head);
+	spin_unlock_irqrestore(&dev_priv->vblank_lock, flags);
+
+	return pending;
+}
+
+static int i915_gem_page_flip(struct drm_device *dev, void *data,
+			      struct drm_file *file_priv)
+{
+	struct drm_i915_gem_page_flip *flip_data = data;
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_gem_object *obj;
+	struct drm_i915_gem_object *obj_priv;
+	unsigned long flags;
+	uint32_t offset;
+	unsigned int pitch, pipe, plane, tiled;
+	int ret = 0, vblank_ref_err = 0, seqno;
+	RING_LOCALS;
+
+	if (!(dev->driver->driver_features & DRIVER_GEM))
+		return -ENODEV;
+
+	/*
+	 * Reject unknown flags so future userspace knows what we (don't)
+	 * support
+	 */
+	if (flip_data->flags & (~I915_PAGE_FLIP_WAIT)) {
+		DRM_ERROR("bad page flip flags\n");
+		return -EINVAL;
+	}
+
+	if ((pipe = flip_data->pipe) > 1) {
+		DRM_ERROR("bad pipe\n");
+		return -EINVAL;
+	}
+
+	plane = i915_pipe_to_plane(dev, pipe);
+	if (plane < 0) {
+		DRM_ERROR("bad pipe (no planes enabled?)\n");
+		return -EINVAL;
+	}
+
+	obj = drm_gem_object_lookup(dev, file_priv, flip_data->handle);
+	if (obj == NULL)
+		return -EBADF;
+
+	/*
+	 * Make sure the new buffer is in bounds
+	 * FIXME: should probably check against current mode as well
+	 */
+	if (flip_data->offset >= obj->size) {
+		DRM_ERROR("bad flip offset\n");
+		ret = -EINVAL;
+		goto out_unref_prelock;
+	}
+
+	obj_priv = obj->driver_private;
+
+	if (i915_gem_flip_pending(obj))
+		wait_for_completion(&obj_priv->vblank);
+
+	mutex_lock(&dev->struct_mutex);
+	if (obj_priv->tiling_mode != I915_TILING_NONE &&
+	    obj_priv->tiling_mode != I915_TILING_X) {
+		DRM_ERROR("can only flip non-tiled or X tiled pages\n");
+		ret = -EINVAL;
+		goto out_unref;
+	}
+
+	vblank_ref_err = drm_vblank_get(dev, pipe);
+	if (!vblank_ref_err) {
+		ret = i915_gem_object_pin(obj, 0);
+		if (ret) {
+			drm_vblank_put(dev, pipe);
+			DRM_ERROR("failed to pin object for flip\n");
+			goto out_unref;
+		}
+	}
+
+	/*
+	 * Put the object in the GTT domain before the flip,
+	 * since there may be outstanding rendering
+	 */
+	ret = i915_gem_object_set_to_gtt_domain(obj, 0);
+	if (ret) {
+		DRM_ERROR("move to GTT failed\n");
+		goto out_unref;
+	}
+
+	offset = obj_priv->gtt_offset + flip_data->offset;
+
+	pitch = obj_priv->stride;
+	tiled = (obj_priv->tiling_mode == I915_TILING_X);
+
+	BEGIN_LP_RING(4);
+	OUT_RING(CMD_OP_DISPLAYBUFFER_INFO | (plane << 20));
+	OUT_RING(pitch);
+	if (IS_I965G(dev)) {
+		OUT_RING(offset | tiled);
+		OUT_RING(((flip_data->x - 1) << 16) | (flip_data->y - 1));
+	} else {
+		OUT_RING(offset);
+		OUT_RING(MI_NOOP);
+	}
+	ADVANCE_LP_RING();
+
+	seqno = i915_add_request(dev, 0);
+
+	mutex_unlock(&dev->struct_mutex);
+
+	/*
+	 * This is a bit racy; the flip above may have already happened
+	 * by the time we get here.  If that happens, the new back buffer
+	 * won't be available for rendering for one extra frame, since
+	 * the vblank list won't have the object.
+	 */
+	spin_lock_irqsave(&dev_priv->vblank_lock, flags);
+	if (!vblank_ref_err)
+		list_add_tail(&obj_priv->vblank_head,
+			      &dev_priv->mm.vblank_list[pipe]);
+
+	obj_priv->flip_seqno = seqno;
+	spin_unlock_irqrestore(&dev_priv->vblank_lock, flags);
+
+	if (!vblank_ref_err && (flip_data->flags & I915_PAGE_FLIP_WAIT))
+		wait_for_completion(&obj_priv->vblank);
+
+out_unref_prelock:
+	/* Take lock again for unref */
+	mutex_lock(&dev->struct_mutex);
+out_unref:
+	drm_gem_object_unreference(obj);
+	mutex_unlock(&dev->struct_mutex);
+
+	return ret;
+}
+
 /**
  * i915_probe_agp - get AGP bootup configuration
  * @pdev: PCI device
@@ -1307,6 +1479,7 @@ struct drm_ioctl_desc i915_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_I915_GEM_SET_TILING, i915_gem_set_tiling, 0),
 	DRM_IOCTL_DEF(DRM_I915_GEM_GET_TILING, i915_gem_get_tiling, 0),
 	DRM_IOCTL_DEF(DRM_I915_GEM_GET_APERTURE, i915_gem_get_aperture_ioctl, 0),
+	DRM_IOCTL_DEF(DRM_I915_GEM_PAGE_FLIP, i915_gem_page_flip, DRM_AUTH|DRM_MASTER),
 };
 
 int i915_max_ioctl = DRM_ARRAY_SIZE(i915_ioctls);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3951a12..148e80a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -159,6 +159,10 @@ typedef struct drm_i915_private {
 	u32 irq_mask_reg;
 	u32 pipestat[2];
 
+	/** Protects vblank list */
+	spinlock_t vblank_lock;
+	struct work_struct vblank_work;
+
 	int tex_lru_log_granularity;
 	int allow_batchbuffer;
 	struct mem_block *agp_heap;
@@ -338,6 +342,11 @@ typedef struct drm_i915_private {
 		 */
 		struct delayed_work retire_work;
 
+		/**
+		 * List of objects waiting on vblank events (one per pipe)
+		 */
+		struct list_head vblank_list[2];
+
 		uint32_t next_gem_seqno;
 
 		/**
@@ -389,6 +398,13 @@ struct drm_i915_gem_object {
 	/** This object's place on the active/flushing/inactive lists */
 	struct list_head list;
 
+	/** Object's place on the vblank list (protected by vblank_lock)*/
+	struct list_head vblank_head;
+	/** sequence number for flip (when it passes the flip is done),
+	 *  protected by vblank lock
+	 */
+	int flip_seqno;
+
 	/**
 	 * This is set if the object is on the active or flushing lists
 	 * (has pending rendering), and is not set if it's on inactive (ready
@@ -457,6 +473,9 @@ struct drm_i915_gem_object {
 
 	/** for phy allocated objects */
 	struct drm_i915_gem_phys_object *phys_obj;
+
+	/** for page flips and other vblank related blocks */
+	struct completion vblank;
 };
 
 /**
@@ -516,6 +535,7 @@ extern long i915_compat_ioctl(struct file *filp, unsigned int cmd,
 extern int i915_emit_box(struct drm_device *dev,
 			 struct drm_clip_rect __user *boxes,
 			 int i, int DR1, int DR4);
+extern bool i915_gem_flip_pending(struct drm_gem_object *obj);
 
 /* i915_irq.c */
 extern int i915_irq_emit(struct drm_device *dev, void *data,
@@ -625,6 +645,9 @@ int i915_gem_attach_phys_object(struct drm_device *dev,
 void i915_gem_detach_phys_object(struct drm_device *dev,
 				 struct drm_gem_object *obj);
 void i915_gem_free_all_phys_object(struct drm_device *dev);
+uint32_t i915_add_request(struct drm_device *dev, uint32_t flush_domains);
+int i915_seqno_passed(uint32_t seq1, uint32_t seq2);
+uint32_t i915_get_gem_seqno(struct drm_device *dev);
 
 /* i915_gem_tiling.c */
 void i915_gem_detect_bit_6_swizzle(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3e025d5..f0996fb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -900,7 +900,7 @@ i915_gem_object_move_to_inactive(struct drm_gem_object *obj)
  *
  * Returned sequence numbers are nonzero on success.
  */
-static uint32_t
+uint32_t
 i915_add_request(struct drm_device *dev, uint32_t flush_domains)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
@@ -1028,7 +1028,7 @@ i915_gem_retire_request(struct drm_device *dev,
 /**
  * Returns true if seq1 is later than seq2.
  */
-static int
+int
 i915_seqno_passed(uint32_t seq1, uint32_t seq2)
 {
 	return (int32_t)(seq1 - seq2) >= 0;
@@ -2498,6 +2498,26 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
 		goto pre_mutex_err;
 	}
 
+	/* Look up object handles */
+	for (i = 0; i < args->buffer_count; i++) {
+		object_list[i] = drm_gem_object_lookup(dev, file_priv,
+						       exec_list[i].handle);
+		if (object_list[i] == NULL) {
+			DRM_ERROR("Invalid object handle %d at index %d\n",
+				   exec_list[i].handle, i);
+			ret = -EBADF;
+			mutex_lock(&dev->struct_mutex);
+			goto err;
+		}
+
+		if (i915_gem_flip_pending(object_list[i])) {
+			struct drm_i915_gem_object *obj_priv;
+
+			obj_priv = object_list[i]->driver_private;
+			wait_for_completion(&obj_priv->vblank);
+		}
+	}
+
 	mutex_lock(&dev->struct_mutex);
 
 	i915_verify_inactive(dev, __FILE__, __LINE__);
@@ -2516,18 +2536,6 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
 		goto pre_mutex_err;
 	}
 
-	/* Look up object handles */
-	for (i = 0; i < args->buffer_count; i++) {
-		object_list[i] = drm_gem_object_lookup(dev, file_priv,
-						       exec_list[i].handle);
-		if (object_list[i] == NULL) {
-			DRM_ERROR("Invalid object handle %d at index %d\n",
-				   exec_list[i].handle, i);
-			ret = -EBADF;
-			goto err;
-		}
-	}
-
 	/* Pin and relocate */
 	for (pin_tries = 0; ; pin_tries++) {
 		ret = 0;
@@ -2920,6 +2928,9 @@ int i915_gem_init_object(struct drm_gem_object *obj)
 	obj_priv->obj = obj;
 	obj_priv->fence_reg = I915_FENCE_REG_NONE;
 	INIT_LIST_HEAD(&obj_priv->list);
+	INIT_LIST_HEAD(&obj_priv->vblank_head);
+
+	init_completion(&obj_priv->vblank);
 
 	return 0;
 }
@@ -2980,8 +2991,10 @@ int
 i915_gem_idle(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj_priv, *tmp;
+	unsigned long irqflags;
 	uint32_t seqno, cur_seqno, last_seqno;
-	int stuck, ret;
+	int stuck, ret, pipe;
 
 	mutex_lock(&dev->struct_mutex);
 
@@ -2995,10 +3008,25 @@ i915_gem_idle(struct drm_device *dev)
 	 */
 	dev_priv->mm.suspended = 1;
 
+	mutex_unlock(&dev->struct_mutex);
+
+	/* Wait for any outstanding flips */
+	spin_lock_irqsave(&dev_priv->vblank_lock, irqflags);
+	for (pipe = 0; pipe < 2; pipe++) {
+		list_for_each_entry_safe(obj_priv, tmp,
+					 &dev_priv->mm.vblank_list[pipe],
+					 vblank_head) {
+			spin_unlock_irqrestore(&dev_priv->vblank_lock, irqflags);
+			wait_for_completion(&obj_priv->vblank);
+			spin_lock_irqsave(&dev_priv->vblank_lock, irqflags);
+		}
+	}
+	spin_unlock_irqrestore(&dev_priv->vblank_lock, irqflags);
+
 	/* Cancel the retire work handler, wait for it to finish if running
 	 */
-	mutex_unlock(&dev->struct_mutex);
 	cancel_delayed_work_sync(&dev_priv->mm.retire_work);
+
 	mutex_lock(&dev->struct_mutex);
 
 	i915_kernel_lost_context(dev);
@@ -3358,9 +3386,12 @@ i915_gem_load(struct drm_device *dev)
 	INIT_LIST_HEAD(&dev_priv->mm.flushing_list);
 	INIT_LIST_HEAD(&dev_priv->mm.inactive_list);
 	INIT_LIST_HEAD(&dev_priv->mm.request_list);
+	INIT_LIST_HEAD(&dev_priv->mm.vblank_list[0]);
+	INIT_LIST_HEAD(&dev_priv->mm.vblank_list[1]);
 	INIT_DELAYED_WORK(&dev_priv->mm.retire_work,
 			  i915_gem_retire_work_handler);
 	dev_priv->mm.next_gem_seqno = 1;
+	spin_lock_init(&dev_priv->vblank_lock);
 
 	/* Old X drivers will take 0-2 for front, back, depth buffers */
 	dev_priv->fence_reg_start = 3;
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 548ff2c..f50df88 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -187,6 +187,36 @@ u32 gm45_get_vblank_counter(struct drm_device *dev, int pipe)
 	return I915_READ(reg);
 }
 
+static void i915_vblank_work_func(struct work_struct *work)
+{
+	drm_i915_private_t *dev_priv = container_of(work, drm_i915_private_t,
+						    vblank_work);
+	struct drm_device *dev = dev_priv->dev;
+	struct drm_i915_gem_object *obj_priv, *tmp;
+	unsigned long irqflags;
+	int pipe, cur_seqno;
+
+	mutex_lock(&dev->struct_mutex);
+
+	spin_lock_irqsave(&dev_priv->vblank_lock, irqflags);
+	for (pipe = 0; pipe < 2; pipe++) {
+		list_for_each_entry_safe(obj_priv, tmp,
+					 &dev_priv->mm.vblank_list[pipe],
+					 vblank_head) {
+			cur_seqno = i915_get_gem_seqno(dev);
+			if (i915_seqno_passed(cur_seqno,
+					      obj_priv->flip_seqno)) {
+				list_del_init(&obj_priv->vblank_head);
+				drm_vblank_put(dev, pipe);
+				i915_gem_object_unpin(obj_priv->obj);
+				complete(&obj_priv->vblank);
+			}
+		}
+	}
+	spin_unlock_irqrestore(&dev_priv->vblank_lock, irqflags);
+	mutex_unlock(&dev->struct_mutex);
+}
+
 irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 {
 	struct drm_device *dev = (struct drm_device *) arg;
@@ -269,6 +299,9 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 			drm_handle_vblank(dev, 1);
 		}
 
+		if (vblank)
+			schedule_work(&dev_priv->vblank_work);
+
 		if ((pipeb_stats & I915_LEGACY_BLC_EVENT_STATUS) ||
 		    (iir & I915_ASLE_INTERRUPT))
 			opregion_asle_intr(dev);
@@ -533,6 +566,7 @@ void i915_driver_irq_preinstall(struct drm_device * dev)
 	I915_WRITE(IMR, 0xffffffff);
 	I915_WRITE(IER, 0x0);
 	(void) I915_READ(IER);
+	INIT_WORK(&dev_priv->vblank_work, i915_vblank_work_func);
 }
 
 int i915_driver_irq_postinstall(struct drm_device *dev)
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index 912cd52..1ac4ded 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -184,6 +184,7 @@ typedef struct _drm_i915_sarea {
 #define DRM_I915_GEM_GET_TILING	0x22
 #define DRM_I915_GEM_GET_APERTURE 0x23
 #define DRM_I915_GEM_MMAP_GTT	0x24
+#define DRM_I915_GEM_PAGE_FLIP	0x25
 
 #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
 #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
@@ -219,6 +220,7 @@ typedef struct _drm_i915_sarea {
 #define DRM_IOCTL_I915_GEM_SET_TILING	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_SET_TILING, struct 
drm_i915_gem_set_tiling)
 #define DRM_IOCTL_I915_GEM_GET_TILING	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_GET_TILING, struct 
drm_i915_gem_get_tiling)
 #define DRM_IOCTL_I915_GEM_GET_APERTURE	DRM_IOR  (DRM_COMMAND_BASE + DRM_I915_GEM_GET_APERTURE, struct 
drm_i915_gem_get_aperture)
+#define DRM_IOCTL_I915_GEM_PAGE_FLIP	DRM_IOW (DRM_COMMAND_BASE + DRM_I915_GEM_PAGE_FLIP, struct 
drm_i915_gem_page_flip)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -654,4 +656,30 @@ struct drm_i915_gem_get_aperture {
 	uint64_t aper_available_size;
 };
 
+#define I915_PAGE_FLIP_WAIT (1<<0) /* block on page flip completion */
+
+struct drm_i915_gem_page_flip {
+	/** Handle of new front buffer */
+	uint32_t handle;
+
+	/** Offset into the object to use */
+	uint64_t offset;
+
+	/**
+	 * page flip flags (wait on flip only for now)
+	 */
+	uint32_t flags;
+
+	/**
+	 * pipe to flip
+	 */
+	uint32_t pipe;
+
+	/**
+	 * screen dimensions for flip
+	 */
+	uint32_t x;
+	uint32_t y;
+};
+
 #endif				/* _I915_DRM_H_ */




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