drm/amd/display: In VRR mode, do DRM core vblank handling at end of vblank. (v2)

In VRR mode, proper vblank/pageflip timestamps can only be computed
after the display scanout position has left front-porch. Therefore
delay calls to drm_crtc_handle_vblank(), and thereby calls to
drm_update_vblank_count() and pageflip event delivery, to after the
end of front-porch when in VRR mode.

We add a new vupdate irq, which triggers at the end of the vupdate
interval, ie. at the end of vblank, and calls the core vblank handler
function. The new irq handler is not executed in standard non-VRR
mode, so vblank handling for fixed refresh rate mode is identical
to the past implementation.

v2: Implement feedback by Nicholas and Paul Menzel.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
index cd10f77cdeb0..fd22b4474dbf 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
@@ -674,11 +674,30 @@ static int amdgpu_dm_set_crtc_irq_state(struct amdgpu_device *adev,
 		__func__);
 }
 
+static int amdgpu_dm_set_vupdate_irq_state(struct amdgpu_device *adev,
+					   struct amdgpu_irq_src *source,
+					   unsigned int crtc_id,
+					   enum amdgpu_interrupt_state state)
+{
+	return dm_irq_state(
+		adev,
+		source,
+		crtc_id,
+		state,
+		IRQ_TYPE_VUPDATE,
+		__func__);
+}
+
 static const struct amdgpu_irq_src_funcs dm_crtc_irq_funcs = {
 	.set = amdgpu_dm_set_crtc_irq_state,
 	.process = amdgpu_dm_irq_handler,
 };
 
+static const struct amdgpu_irq_src_funcs dm_vupdate_irq_funcs = {
+	.set = amdgpu_dm_set_vupdate_irq_state,
+	.process = amdgpu_dm_irq_handler,
+};
+
 static const struct amdgpu_irq_src_funcs dm_pageflip_irq_funcs = {
 	.set = amdgpu_dm_set_pflip_irq_state,
 	.process = amdgpu_dm_irq_handler,
@@ -695,6 +714,9 @@ void amdgpu_dm_set_irq_funcs(struct amdgpu_device *adev)
 	adev->crtc_irq.num_types = adev->mode_info.num_crtc;
 	adev->crtc_irq.funcs = &dm_crtc_irq_funcs;
 
+	adev->vupdate_irq.num_types = adev->mode_info.num_crtc;
+	adev->vupdate_irq.funcs = &dm_vupdate_irq_funcs;
+
 	adev->pageflip_irq.num_types = adev->mode_info.num_crtc;
 	adev->pageflip_irq.funcs = &dm_pageflip_irq_funcs;