[PATCH] drm/radeon: Resume fbcon last

[Daniel Vetter]

So a few people complained that

commit 177cf92de4aa97ec1435987e91696ed8b5023130
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Tue Apr 1 22:14:59 2014 +0200

    drm/crtc-helpers: fix dpms on logic

which was merged into 3.15-rc1, broke resume on radeons. Strangely git
bisect lead everyone to

commit 25f397a429dfa43f22c278d0119a60a343aa568f
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Fri Jul 19 18:57:11 2013 +0200

    drm/crtc-helper: explicit DPMS on after modeset

which was merged long ago and actually part of 3.14.

Digging deeper I've noticed (again) that with these changes the call
to drm_helper_resume_force_mode in the radeon resume handlers was a
no-op previously because everything gets shut down on suspend. radeon
does this with explicit calls to drm_helper_connector_dpms with
DPMS_OFF. But with 177c we now force the dpms state to ON, so suddenly
resume_force_mode actually forced something.

This was the intention of the change after all, the problem is that
radeon resumes the fbdev console layer _before_ restoring the display,
through calling fb_set_suspend. And fbcon does an immediate ->set_par,
which in turn causes the same force mode restore to happen.

Two concurrent modeset operations didn't lead to happiness. Fix this
by delaying the fbcon resume until the end of the readeon resum
functions.

References: https://lkml.org/lkml/2014/5/29/1043
References: https://lkml.org/lkml/2014/5/2/388
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=74751
Tested-by: Ken Moffat <zarniwhoop at ntlworld.com>
Cc: Alex Deucher <alexdeucher at gmail.com>
Cc: Ken Moffat <zarniwhoop at ntlworld.com>
Cc: Dave Airlie <airlied at redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/radeon/radeon_device.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 9aa1afd1786e..8f434c6c4540 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1533,11 +1533,6 @@ int radeon_resume_kms(struct drm_device *dev, bool resume, bool fbcon)
 
 	radeon_restore_bios_scratch_regs(rdev);
 
-	if (fbcon) {
-		radeon_fbdev_set_suspend(rdev, 0);
-		console_unlock();
-	}
-
 	/* init dig PHYs, disp eng pll */
 	if (rdev->is_atom_bios) {
 		radeon_atom_encoder_init(rdev);
@@ -1562,6 +1557,12 @@ int radeon_resume_kms(struct drm_device *dev, bool resume, bool fbcon)
 	}
 
 	drm_kms_helper_poll_enable(dev);
+
+	if (fbcon) {
+		radeon_fbdev_set_suspend(rdev, 0);
+		console_unlock();
+	}
+
 	return 0;
 }
 
-- 
1.9.2