drm/atomic-helper: Add atomic_disable CRTC helper callback

Some display controllers need plane(s) to be disabled together with
the relevant CRTC, e.g., the IPUv3 display controller for imx-drm.
This patch adds atomic_disable CRTC helper callback so that
old_crtc_state(as a parameter of the callback) could be used
to get the active plane(s) of the old CRTC state for disable operation.

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Liu Ying <gnuiyl@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1472196644-30563-2-git-send-email-gnuiyl@gmail.com

2 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 9abe0a242f96..4828b9b860de 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -749,6 +749,8 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
                 /* Right function depends upon target state. */
                 if (crtc->state->enable && funcs->prepare)
                         funcs->prepare(crtc);
+                else if (funcs->atomic_disable)
+                        funcs->atomic_disable(crtc, old_crtc_state);
                 else if (funcs->disable)
                         funcs->disable(crtc);
                 else
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index 6c8d3dad66ec..10e449c86dbd 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -266,6 +266,8 @@ struct drm_crtc_helper_funcs {
          * disable anything at the CRTC level. To ensure that runtime PM
          * handling (using either DPMS or the new "ACTIVE" property) works
          * @disable must be the inverse of @enable for atomic drivers.
+         * Atomic drivers should consider to use @atomic_disable instead of
+         * this one.
          *
          * NOTE:
          *
@@ -391,6 +393,28 @@ struct drm_crtc_helper_funcs {
          */
         void (*atomic_flush)(struct drm_crtc *crtc,
                              struct drm_crtc_state *old_crtc_state);
+
+        /**
+         * @atomic_disable:
+         *
+         * This callback should be used to disable the CRTC. With the atomic
+         * drivers it is called after all encoders connected to this CRTC have
+         * been shut off already using their own ->disable hook. If that
+         * sequence is too simple drivers can just add their own hooks and call
+         * it from this CRTC callback here by looping over all encoders
+         * connected to it using for_each_encoder_on_crtc().
+         *
+         * This hook is used only by atomic helpers. Atomic drivers don't
+         * need to implement it if there's no need to disable anything at the
+         * CRTC level.
+         *
+         * Comparing to @disable, this one provides the additional input
+         * parameter @old_crtc_state which could be used to access the old
+         * state. Atomic drivers should consider to use this one instead
+         * of @disable.
+         */
+        void (*atomic_disable)(struct drm_crtc *crtc,
+                               struct drm_crtc_state *old_crtc_state);
 };
 
 /**