drm: Pass CRTC ID in userspace vblank events

With the atomic API, it is possible that a single commit affects
multiple crtcs. If the user requests an event with that commit, one
event will be sent for each CRTC, but it is not possible to distinguish
which crtc an event is for in user space. To solve this, the reserved
field in struct drm_vblank_event is repurposed to include the crtc_id
which the event is for.

The DRM_CAP_CRTC_IN_VBLANK_EVENT is added to allow userspace to query if
the crtc field will be set properly.

[daniels: Rebased, using Maarten's forward-port.]

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Stone <daniels@collabora.com>
Cc: Maarten Lankhorst <maarten.lankhorst@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170404165221.28240-2-daniels@collabora.com

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index dac1b2593cb1..8c866cac62dd 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1026,6 +1026,7 @@ void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
 
         e->pipe = pipe;
         e->event.sequence = drm_vblank_count(dev, pipe);
+        e->event.crtc_id = crtc->base.id;
         list_add_tail(&e->base.link, &dev->vblank_event_list);
 }
 EXPORT_SYMBOL(drm_crtc_arm_vblank_event);
@@ -1056,6 +1057,7 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
                 now = get_drm_timestamp();
         }
         e->pipe = pipe;
+        e->event.crtc_id = crtc->base.id;
         send_vblank_event(dev, e, seq, &now);
 }
 EXPORT_SYMBOL(drm_crtc_send_vblank_event);