From: Mario Kleiner <mario.kleiner.de@gmail.com>
Date: Wed, 21 Jun 2017 03:44:55 +0200
Subject: drm/radeon: Allow vblank_disable_immediate.
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Git-commit: 08d3874636a20b8852f8eea1c6ad1054234c9ae6
Patch-mainline: v4.14-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

With instantaneous high precision vblank timestamping
that updates at leading edge of vblank, a cooked hw
vblank counter which increments at leading edge of
vblank, and reliable page flip execution and completion
at leading edge of vblank, we should meet the requirements
for fast/immediate vblank irq disable/enable.

Testing on Linux-4.12-rc5 + drm-next on a Radeon HD 5770
(DCE 4) with timing measurement equipment indicates this
works fine, so allow immediate vblank disable for power
saving.

For debugging in case of unexpected trouble, booting
with kernel cmdline option drm.vblankoffdelay=0
(or echo 0 > /sys/module/drm/parameters/vblankoffdelay)
would keep vblank irqs permanently on to approximate old
behavior.

Reviewed-and-Tested-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/radeon/radeon_irq_kms.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
@@ -283,6 +283,10 @@ int radeon_irq_kms_init(struct radeon_de
 	int r = 0;
 
 	spin_lock_init(&rdev->irq.lock);
+
+	/* Disable vblank irqs aggressively for power-saving */
+	rdev->ddev->vblank_disable_immediate = true;
+
 	r = drm_vblank_init(rdev->ddev, rdev->num_crtc);
 	if (r) {
 		return r;