[Intel-gfx] [PATCH] drm/i915: Make sure we invalidate frontbuffer on fbcon.

[Rodrigo Vivi]

There are some cases like suspend/resume or dpms off/on sequences
that can flush frontbuffer bits. In these cases features that relies
on frontbuffer tracking can start working and user can stop getting
screen updates on fbcon having impression the system is frozen.

So, let's make sure we also invalidate frontbuffer on fbdev blank.

v2: Daniel was right, backtrace didn't show other path than this blank
one so let's make sure frontbuffer bits gets invalidate here instead of
on random write operations that doesn't garantee we track all frontbuffer
writes.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/i915/intel_fbdev.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 234a699..324b160 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -71,6 +71,40 @@ static int intel_fbdev_set_par(struct fb_info *info)
 	return ret;
 }
 
+static int intel_fbdev_blank(int blank, struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct intel_fbdev *ifbdev =
+		container_of(fb_helper, struct intel_fbdev, helper);
+	int ret;
+
+	ret = drm_fb_helper_blank(blank, info);
+
+	if (ret == 0) {
+		/*
+		 * FIXME: After dpms off/on sequence on fbdev frontbuffer bits
+		 * gets flushed so, let's set to gtt domain again when
+		 * restoring the panel, at least while we don't have a
+		 * propper solution.
+		  */
+		mutex_lock(&fb_helper->dev->struct_mutex);
+
+		/*
+		 * There are some cases that can flush frontbuffer bits
+		 * while we are still on console. Like when planes gets
+		 * enabled/disabled on blank/unblank. So, let's be sure
+		 * the fb obj gets invalidated when touching blank function.
+		 * It is already on gtt domain, so we just invalidate it
+		 * making sure components trusting frontbuffer tracking
+		 * still gets invalidate after blank/unblank sequence.
+		 */
+		intel_fb_obj_invalidate(ifbdev->fb->obj, NULL, ORIGIN_GTT);
+		mutex_unlock(&fb_helper->dev->struct_mutex);
+	}
+
+	return ret;
+}
+
 static struct fb_ops intelfb_ops = {
 	.owner = THIS_MODULE,
 	.fb_check_var = drm_fb_helper_check_var,
@@ -79,7 +113,7 @@ static struct fb_ops intelfb_ops = {
 	.fb_copyarea = cfb_copyarea,
 	.fb_imageblit = cfb_imageblit,
 	.fb_pan_display = drm_fb_helper_pan_display,
-	.fb_blank = drm_fb_helper_blank,
+	.fb_blank = intel_fbdev_blank,
 	.fb_setcmap = drm_fb_helper_setcmap,
 	.fb_debug_enter = drm_fb_helper_debug_enter,
 	.fb_debug_leave = drm_fb_helper_debug_leave,
-- 
2.1.0