[PATCH] drm/simple-helpers: Always add planes to the state update

[Daniel Vetter]

Our update function is hooked to the single plane, which might not get
called for crtc-only updates. Which is surprising, so fix this by
always adding the plane.

While at it document how&when the event should be sent out better in
the kerneldoc.

Cc: Noralf Trønnes <noralf at tronnes.org>
Cc: andrea.merello at gmail.com
Tested-and-Reported-by: andrea.merello at gmail.com
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
I'm not entirely sure we really want to put the responsibility for
this onto driver. Plan B) would be to remove the kerneldoc I added
here and call the right function from drm_simple_kms_plane_atomic_update.
That way simple drivers don't need to deal with that detail, and in
general those drivers don't care that much about the miniscule
possible race a generic implementation would cause. What do you
suggest as the best approach?
-Daniel
---
 drivers/gpu/drm/drm_simple_kms_helper.c | 7 +++++++
 include/drm/drm_simple_kms_helper.h     | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index bada17166512..447631018426 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -34,6 +34,12 @@ static const struct drm_encoder_funcs drm_simple_kms_encoder_funcs = {
 	.destroy = drm_encoder_cleanup,
 };
 
+static int drm_simple_kms_crtc_check(struct drm_crtc *crtc,
+				     struct drm_crtc_state *state)
+{
+	return drm_atomic_add_affected_planes(state->state, crtc);
+}
+
 static void drm_simple_kms_crtc_enable(struct drm_crtc *crtc)
 {
 	struct drm_simple_display_pipe *pipe;
@@ -57,6 +63,7 @@ static void drm_simple_kms_crtc_disable(struct drm_crtc *crtc)
 }
 
 static const struct drm_crtc_helper_funcs drm_simple_kms_crtc_helper_funcs = {
+	.atomic_check = drm_simple_kms_crtc_check,
 	.disable = drm_simple_kms_crtc_disable,
 	.enable = drm_simple_kms_crtc_enable,
 };
diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
index 269039722f91..826946ca2b82 100644
--- a/include/drm/drm_simple_kms_helper.h
+++ b/include/drm/drm_simple_kms_helper.h
@@ -60,6 +60,12 @@ struct drm_simple_display_pipe_funcs {
 	 *
 	 * This function is called when the underlying plane state is updated.
 	 * This hook is optional.
+	 *
+	 * This is the function drivers should submit the
+	 * &drm_pending_vblank_event from. Using either
+	 * drm_crtc_arm_vblank_event(), when the driver supports vblank
+	 * interrupt handling, or drm_crtc_send_vblank_event() directly in case
+	 * the hardware lacks vblank support entirely.
 	 */
 	void (*update)(struct drm_simple_display_pipe *pipe,
 		       struct drm_plane_state *plane_state);
-- 
2.8.1