[Intel-gfx] [PATCH 1/4] drm/i915: Make fb user dirty operation to invalidate frontbuffer

[Rodrigo Vivi]

This patch introduces a frontbuffer invalidation on dirty fb
user callback.

It is mainly used for DIRTYFB drm ioctl, but can be extended
for fbdev use on following patch.

This patch itself already solves the biggest PSR known issue, that is
missed screen updates during boot, mainly when there is a splash
screen involved like plymouth.

Plymoth will do a modeset over ioctl that flushes frontbuffer
tracking and PSR gets back to work while it cannot track the
screen updates and exit properly. However plymouth also uses
a dirtyfb ioctl whenever updating the screen. So let's use it
to invalidate PSR back again.

This patch also introduces the ORIGIN_FB_DIRTY to frontbuffer tracking.
The reason is that whenever using this invalidate path we don't need to
keep continuously invalidating the frontbuffer for every call. One call
between flips is enough to keep frontbuffer tracking invalidated and
let all users aware. If a sync or async flip completed it means that we
probably can flush everything and enable powersavings features back.
If this isn't the case on the next dirty call we invalidate it again
until next flip.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h          |  2 ++
 drivers/gpu/drm/i915/intel_display.c     | 18 ++++++++++++++++++
 drivers/gpu/drm/i915/intel_frontbuffer.c | 18 ++++++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ea9caf2..e0591d3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -889,6 +889,7 @@ enum fb_op_origin {
 	ORIGIN_CPU,
 	ORIGIN_CS,
 	ORIGIN_FLIP,
+	ORIGIN_FB_DIRTY,
 };
 
 struct i915_fbc {
@@ -1628,6 +1629,7 @@ struct i915_frontbuffer_tracking {
 	 */
 	unsigned busy_bits;
 	unsigned flip_bits;
+	bool fb_dirty;
 };
 
 struct i915_wa_reg {
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 01eaab8..19c2ab3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14330,9 +14330,27 @@ static int intel_user_framebuffer_create_handle(struct drm_framebuffer *fb,
 	return drm_gem_handle_create(file, &obj->base, handle);
 }
 
+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 drm_device *dev = fb->dev;
+	struct intel_framebuffer *intel_fb = to_intel_framebuffer(fb);
+	struct drm_i915_gem_object *obj = intel_fb->obj;
+
+	mutex_lock(&dev->struct_mutex);
+	intel_fb_obj_invalidate(obj, ORIGIN_FB_DIRTY);
+	mutex_unlock(&dev->struct_mutex);
+
+	return 0;
+}
+
 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,
 };
 
 static
diff --git a/drivers/gpu/drm/i915/intel_frontbuffer.c b/drivers/gpu/drm/i915/intel_frontbuffer.c
index 6e90e2b..329b6fc 100644
--- a/drivers/gpu/drm/i915/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/intel_frontbuffer.c
@@ -81,12 +81,28 @@ void intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
 {
 	struct drm_device *dev = obj->base.dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
+	bool fb_dirty;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
 	if (!obj->frontbuffer_bits)
 		return;
 
+	/*
+	 * We just invalidate the frontbuffer on the first dirty and keep
+	 * it dirty and invalid until next flip.
+	 */
+	if (origin == ORIGIN_FB_DIRTY) {
+		mutex_lock(&dev_priv->fb_tracking.lock);
+		fb_dirty = dev_priv->fb_tracking.fb_dirty;
+		dev_priv->fb_tracking.fb_dirty = true;
+		mutex_unlock(&dev_priv->fb_tracking.lock);
+
+		if (fb_dirty)
+			return;
+		DRM_ERROR("PSR FBT invalidate dirty\n");
+	}
+
 	if (origin == ORIGIN_CS) {
 		mutex_lock(&dev_priv->fb_tracking.lock);
 		dev_priv->fb_tracking.busy_bits
@@ -207,6 +223,7 @@ void intel_frontbuffer_flip_complete(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
 	mutex_lock(&dev_priv->fb_tracking.lock);
+	dev_priv->fb_tracking.fb_dirty = false;
 	/* Mask any cancelled flips. */
 	frontbuffer_bits &= dev_priv->fb_tracking.flip_bits;
 	dev_priv->fb_tracking.flip_bits &= ~frontbuffer_bits;
@@ -233,6 +250,7 @@ void intel_frontbuffer_flip(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
 	mutex_lock(&dev_priv->fb_tracking.lock);
+	dev_priv->fb_tracking.fb_dirty = false;
 	/* Remove stale busy bits due to the old buffer. */
 	dev_priv->fb_tracking.busy_bits &= ~frontbuffer_bits;
 	mutex_unlock(&dev_priv->fb_tracking.lock);
-- 
2.1.0