[PATCH 4/5] drm/i915: Track modifications to the frontbuffer

[Chris Wilson <chris@chris-wilson.co.uk>]

The frontbuffer (active framebuffer being used as the scanout) often
requires addition work to flush any modifications to the display engine
and to the displays. So in order to do so, we need to detect whenever we
begin to write to the frontbuffer and mark it for a flush. The flush
then is performed after a slight delay, in order to coalesce several
small updates into a single flush.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_debugfs.c        |   2 +
 drivers/gpu/drm/i915/i915_drv.h            |   4 +
 drivers/gpu/drm/i915/i915_gem.c            |   4 +
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   2 +-
 drivers/gpu/drm/i915/intel_display.c       | 122 ++++++++++++++++++++++++++---
 drivers/gpu/drm/i915/intel_drv.h           |   5 ++
 include/uapi/drm/i915_drm.h                |   1 +
 7 files changed, 130 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index d8deb3b..db9af99 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -138,6 +138,8 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
 	}
 	if (obj->ring != NULL)
 		seq_printf(m, " (%s)", obj->ring->name);
+	if (!list_empty(&obj->fb_list))
+		seq_printf(m, " (framebuffer)");
 }
 
 static int i915_gem_object_list_info(struct seq_file *m, void *data)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 01901b5..1257e0e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1064,6 +1064,8 @@ typedef struct drm_i915_private {
 	u32 hpd_event_bits;
 	struct timer_list hotplug_reenable_timer;
 
+	struct delayed_work display_refresh_work;
+
 	int num_plane;
 
 	unsigned long cfb_size;
@@ -1308,6 +1310,8 @@ struct drm_i915_gem_object {
 	unsigned int has_global_gtt_mapping:1;
 	unsigned int has_dma_mapping:1;
 
+	struct list_head fb_list;
+
 	struct sg_table *pages;
 	int pages_pin_count;
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 030b742..6661adb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3321,6 +3321,9 @@ i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
 		obj->base.read_domains = I915_GEM_DOMAIN_GTT;
 		obj->base.write_domain = I915_GEM_DOMAIN_GTT;
 		obj->dirty = 1;
+
+		if (obj->pin_count && !list_empty(&obj->fb_list))
+			intel_mark_fb_busy(obj, NULL);
 	}
 
 	trace_i915_gem_object_change_domain(obj,
@@ -3890,6 +3893,7 @@ unlock:
 void i915_gem_object_init(struct drm_i915_gem_object *obj,
 			  const struct drm_i915_gem_object_ops *ops)
 {
+	INIT_LIST_HEAD(&obj->fb_list);
 	INIT_LIST_HEAD(&obj->mm_list);
 	INIT_LIST_HEAD(&obj->global_list);
 	INIT_LIST_HEAD(&obj->ring_list);
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 73974fa..dabd9af 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -785,7 +785,7 @@ i915_gem_execbuffer_move_to_active(struct list_head *objects,
 		if (obj->base.write_domain) {
 			obj->dirty = 1;
 			obj->last_write_seqno = intel_ring_get_seqno(ring);
-			if (obj->pin_count) /* check for potential scanout */
+			if (obj->pin_count && !list_empty(&obj->fb_list))
 				intel_mark_fb_busy(obj, ring);
 		}
 
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 821a52d..be60f12 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6663,7 +6663,9 @@ intel_framebuffer_create(struct drm_device *dev,
 		return ERR_PTR(-ENOMEM);
 	}
 
+	mutex_lock(&dev->struct_mutex);
 	ret = intel_framebuffer_init(dev, intel_fb, mode_cmd, obj);
+	mutex_unlock(&dev->struct_mutex);
 	if (ret) {
 		drm_gem_object_unreference_unlocked(&obj->base);
 		kfree(intel_fb);
@@ -7084,25 +7086,94 @@ void intel_mark_idle(struct drm_device *dev)
 	}
 }
 
-void intel_mark_fb_busy(struct drm_i915_gem_object *obj,
-			struct intel_ring_buffer *ring)
+static void intel_display_refresh(struct work_struct *work)
 {
-	struct drm_device *dev = obj->base.dev;
+	struct drm_i915_private *dev_priv =
+		container_of(work, struct drm_i915_private, display_refresh_work.work);
+	struct drm_device *dev = dev_priv->dev;
 	struct drm_crtc *crtc;
+	u32 rings = 0;
+	u32 flush = 0;
 
-	if (!i915_powersave)
-		return;
+	mutex_lock(&dev->struct_mutex);
 
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		struct intel_framebuffer *fb = to_intel_framebuffer(crtc->fb);
+
 		if (!crtc->fb)
 			continue;
 
-		if (to_intel_framebuffer(crtc->fb)->obj != obj)
+		/* kick PSR/FBC/GFDT etc */
+
+		if (!fb->refresh_pending)
+			continue;
+
+		if (fb->refresh_mode == REFRESH_NONE)
+			i915_gem_release_mmap(fb->obj);
+		fb->obj->base.write_domain &= ~I915_GEM_DOMAIN_GTT;
+		fb->refresh_pending = false;
+	}
+
+	if (flush) {
+		struct intel_ring_buffer *ring;
+		int i;
+
+		if (rings == 0)
+			rings = 1 << BCS;
+
+		for_each_ring(ring, dev_priv, i)
+			if (rings & (1 << i))
+				(void)intel_ring_flush_internal(ring, flush);
+	}
+
+	mutex_unlock(&dev->struct_mutex);
+}
+
+static void __intel_mark_fb_busy(struct intel_framebuffer *fb,
+				 struct intel_ring_buffer *ring)
+{
+	struct drm_device *dev = fb->base.dev;
+	struct drm_crtc *crtc;
+	bool refresh = false;
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		if (crtc->fb != &fb->base)
 			continue;
 
 		intel_increase_pllclock(crtc);
-		if (ring && intel_fbc_enabled(dev))
-			ring->fbc_dirty = true;
+		refresh = true;
+	}
+
+	if (!refresh || fb->refresh_pending)
+		return;
+
+	refresh = false;
+
+	if (ring && intel_fbc_enabled(dev)) {
+		ring->fbc_dirty = true;
+		refresh = true;
+	}
+
+	if (refresh) {
+		struct drm_i915_private *dev_priv = dev->dev_private;
+
+		fb->refresh_pending = true;
+		queue_delayed_work(dev_priv->wq,
+				   &dev_priv->display_refresh_work,
+				   msecs_to_jiffies(20));
+	}
+}
+
+void intel_mark_fb_busy(struct drm_i915_gem_object *obj,
+			struct intel_ring_buffer *ring)
+{
+	struct intel_framebuffer *fb;
+
+	list_for_each_entry(fb, &obj->fb_list, obj_list) {
+		if (fb->refresh_mode == REFRESH_USER)
+			continue;
+
+		__intel_mark_fb_busy(fb, NULL);
 	}
 }
 
@@ -9071,12 +9142,31 @@ static void intel_setup_outputs(struct drm_device *dev)
 	drm_helper_move_panel_connectors_to_head(dev);
 }
 
+static int intel_user_framebuffer_dirty(struct drm_framebuffer *fb,
+					struct drm_file *file,
+					unsigned flags, unsigned color,
+					struct drm_clip_rect *clips,
+					unsigned num_clips)
+{
+	struct intel_framebuffer *intel_fb = to_intel_framebuffer(fb);
+
+	if (intel_fb->refresh_mode == REFRESH_USER)
+		__intel_mark_fb_busy(intel_fb, NULL);
+
+	return 0;
+}
+
 static void intel_user_framebuffer_destroy(struct drm_framebuffer *fb)
 {
 	struct intel_framebuffer *intel_fb = to_intel_framebuffer(fb);
+	struct drm_device *dev = fb->dev;
 
 	drm_framebuffer_cleanup(fb);
-	drm_gem_object_unreference_unlocked(&intel_fb->obj->base);
+
+	mutex_lock(&dev->struct_mutex);
+	list_del(&intel_fb->obj_list);
+	drm_gem_object_unreference(&intel_fb->obj->base);
+	mutex_unlock(&dev->struct_mutex);
 
 	kfree(intel_fb);
 }
@@ -9094,6 +9184,7 @@ static int intel_user_framebuffer_create_handle(struct drm_framebuffer *fb,
 static const struct drm_framebuffer_funcs intel_fb_funcs = {
 	.destroy = intel_user_framebuffer_destroy,
 	.create_handle = intel_user_framebuffer_create_handle,
+	.dirty = intel_user_framebuffer_dirty,
 };
 
 int intel_framebuffer_init(struct drm_device *dev,
@@ -9174,6 +9265,8 @@ int intel_framebuffer_init(struct drm_device *dev,
 	drm_helper_mode_fill_fb_struct(&intel_fb->base, mode_cmd);
 	intel_fb->obj = obj;
 	intel_fb->powersave = true;
+	intel_fb->refresh_mode = REFRESH_NONE;
+	intel_fb->refresh_pending = false;
 
 	ret = drm_framebuffer_init(dev, &intel_fb->base, &intel_fb_funcs);
 	if (ret) {
@@ -9181,6 +9274,8 @@ int intel_framebuffer_init(struct drm_device *dev,
 		return ret;
 	}
 
+	list_add(&intel_fb->obj_list, &obj->fb_list);
+
 	return 0;
 }
 
@@ -9207,6 +9302,9 @@ __intel_user_framebuffer_getparam(struct intel_framebuffer *fb,
 	case INTEL_FRAMEBUFFER_PARAM_POWERSAVE:
 		*value = fb->powersave;
 		return 0;
+	case INTEL_FRAMEBUFFER_PARAM_REFRESH:
+		*value = fb->refresh_mode;
+		return 0;
 	default:
 		return -EINVAL;
 	}
@@ -9243,6 +9341,9 @@ __intel_user_framebuffer_setparam(struct intel_framebuffer *fb,
 	case INTEL_FRAMEBUFFER_PARAM_POWERSAVE:
 		fb->powersave = value;
 		return 0;
+	case INTEL_FRAMEBUFFER_PARAM_REFRESH:
+		fb->refresh_mode = value;
+		return 0;
 	default:
 		return -EINVAL;
 	}
@@ -9616,6 +9717,9 @@ void intel_modeset_init(struct drm_device *dev)
 
 	/* Just in case the BIOS is doing something questionable. */
 	intel_disable_fbc(dev);
+
+	INIT_DELAYED_WORK(&dev_priv->display_refresh_work,
+			  intel_display_refresh);
 }
 
 static void
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 4cddefb..9f32949 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -103,6 +103,11 @@ struct intel_framebuffer {
 	struct drm_framebuffer base;
 	struct drm_i915_gem_object *obj;
 	unsigned powersave:1;
+	unsigned refresh_mode:1;
+#define REFRESH_NONE 0
+#define REFRESH_USER 1
+	unsigned refresh_pending:1;
+	struct list_head obj_list;
 };
 
 struct intel_fbdev {
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 74c34c2..609fc0c 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1006,6 +1006,7 @@ struct intel_framebuffer_param {
 	__u32 fb_id;
 	__u32 param;
 #define INTEL_FRAMEBUFFER_PARAM_POWERSAVE 1
+#define INTEL_FRAMEBUFFER_PARAM_REFRESH 2
 	__u64 value;
 };
 
-- 
1.8.3.1