[Intel-gfx] [PATCH] drm/fb-helper: Restore first connection behaviour on deferred setup

[Liviu Dudau]

Prior to commit b0aa06e9a7fd ("drm/fb-helper: Support deferred setup"),
if no output is connected at framebuffer setup time, we get a default
1024x768 mode that is going to be used when we first connect a monitor.
After the commit, on first connection after deferred setup, we probe
the monitor and get the preferred resolution, but no mode get set
because the drm_fb_helper_hotplug_event() function returns early
when the setup has been deferred. That is different from what happens
on a second re-connect of the monitor, when the native mode get set.

Create a more consistent behaviour by checking in the
drm_fb_helper_hotplug_event() function if the deferred setup is still
active. If not, that means we now have a valid framebuffer that can be
used for setting the correct mode.

Fixes: b0aa06e9a7fd ("drm/fb-helper: Support deferred setup")
Signed-off-by: Liviu Dudau <Liviu.Dudau at arm.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_fb_helper.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index d833eb2320d1..bb7b44d284ec 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -2444,6 +2444,7 @@ static int __drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper,
 		if (ret == -EAGAIN) {
 			fb_helper->preferred_bpp = bpp_sel;
 			fb_helper->deferred_setup = true;
+			ret = 0;
 		}
 		mutex_unlock(&fb_helper->lock);
 
@@ -2565,7 +2566,13 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
 	if (fb_helper->deferred_setup) {
 		err = __drm_fb_helper_initial_config(fb_helper,
 						     fb_helper->preferred_bpp);
-		return err;
+		/*
+		 * __drm_fb_helper_initial_config can change deferred_setup,
+		 * if 'false' that means we can go ahead with the rest of
+		 * the setup as normal
+		 */
+		if (fb_helper->deferred_setup)
+			return err;
 	}
 
 	if (!fb_helper->fb || !drm_fb_helper_is_bound(fb_helper)) {
-- 
2.13.1