[PATCH v2 2/4] drm/vblank: Add CRTC helpers for simple use cases

[Thomas Zimmermann <tzimmermann@suse.de>]

Implement atomic_flush, atomic_enable and atomic_disable of struct
drm_crtc_helper_funcs for vblank handling. Driver with no further
requirements can use these functions instead of adding their own.
Also simplifies the use of vblank timers.

v2:
- fix docs

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_vblank_helper.c | 80 +++++++++++++++++++++++++++++
 include/drm/drm_vblank_helper.h     | 23 +++++++++
 2 files changed, 103 insertions(+)

diff --git a/drivers/gpu/drm/drm_vblank_helper.c b/drivers/gpu/drm/drm_vblank_helper.c
index f94d1e706191..a04a6ba1b0ca 100644
--- a/drivers/gpu/drm/drm_vblank_helper.c
+++ b/drivers/gpu/drm/drm_vblank_helper.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: MIT
 
+#include <drm/drm_atomic.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_modeset_helper_vtables.h>
@@ -17,6 +18,12 @@
  * Drivers enable support for vblank timers by setting the vblank callbacks
  * in struct &drm_crtc_funcs to the helpers provided by this library. The
  * initializer macro DRM_CRTC_VBLANK_TIMER_FUNCS does this conveniently.
+ * The driver further has to send the VBLANK event from its atomic_flush
+ * callback and control vblank from the CRTC's atomic_enable and atomic_disable
+ * callbacks. The callbacks are located in struct &drm_crtc_helper_funcs.
+ * The vblank helper library provides implementations of these callbacks
+ * for drivers without further requirements. The initializer macro
+ * DRM_CRTC_HELPER_VBLANK_FUNCS sets them coveniently.
  *
  * Once the driver enables vblank support with drm_vblank_init(), each
  * CRTC's vblank timer fires according to the programmed display mode. By
@@ -25,6 +32,79 @@
  * struct &drm_crtc_helper_funcs.handle_vblank_timeout.
  */
 
+/*
+ * VBLANK helpers
+ */
+
+/**
+ * drm_crtc_vblank_atomic_flush -
+ *	Implements struct &drm_crtc_helper_funcs.atomic_flush
+ * @crtc: The CRTC
+ * @state: The atomic state to apply
+ *
+ * The helper drm_crtc_vblank_atomic_flush() implements atomic_flush of
+ * struct drm_crtc_helper_funcs for CRTCs that only need to send out a
+ * VBLANK event.
+ *
+ * See also struct &drm_crtc_helper_funcs.atomic_flush.
+ */
+void drm_crtc_vblank_atomic_flush(struct drm_crtc *crtc,
+				  struct drm_atomic_state *state)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+	struct drm_pending_vblank_event *event;
+
+	spin_lock_irq(&dev->event_lock);
+
+	event = crtc_state->event;
+	crtc_state->event = NULL;
+
+	if (event) {
+		if (drm_crtc_vblank_get(crtc) == 0)
+			drm_crtc_arm_vblank_event(crtc, event);
+		else
+			drm_crtc_send_vblank_event(crtc, event);
+	}
+
+	spin_unlock_irq(&dev->event_lock);
+}
+EXPORT_SYMBOL(drm_crtc_vblank_atomic_flush);
+
+/**
+ * drm_crtc_vblank_atomic_enable - Implements struct &drm_crtc_helper_funcs.atomic_enable
+ * @crtc: The CRTC
+ * @state: The atomic state
+ *
+ * The helper drm_crtc_vblank_atomic_enable() implements atomic_enable
+ * of struct drm_crtc_helper_funcs for CRTCs the only need to enable VBLANKs.
+ *
+ * See also struct &drm_crtc_helper_funcs.atomic_enable.
+ */
+void drm_crtc_vblank_atomic_enable(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	drm_crtc_vblank_on(crtc);
+}
+EXPORT_SYMBOL(drm_crtc_vblank_atomic_enable);
+
+/**
+ * drm_crtc_vblank_atomic_disable - Implements struct &drm_crtc_helper_funcs.atomic_disable
+ * @crtc: The CRTC
+ * @state: The atomic state
+ *
+ * The helper drm_crtc_vblank_atomic_disable() implements atomic_disable
+ * of struct drm_crtc_helper_funcs for CRTCs the only need to disable VBLANKs.
+ *
+ * See also struct &drm_crtc_funcs.atomic_disable.
+ */
+void drm_crtc_vblank_atomic_disable(struct drm_crtc *crtc,
+				    struct drm_atomic_state *state)
+{
+	drm_crtc_vblank_off(crtc);
+}
+EXPORT_SYMBOL(drm_crtc_vblank_atomic_disable);
+
 /*
  * VBLANK timer
  */
diff --git a/include/drm/drm_vblank_helper.h b/include/drm/drm_vblank_helper.h
index 74a971d0cfba..fcd8a9b35846 100644
--- a/include/drm/drm_vblank_helper.h
+++ b/include/drm/drm_vblank_helper.h
@@ -6,8 +6,31 @@
 #include <linux/hrtimer_types.h>
 #include <linux/types.h>
 
+struct drm_atomic_state;
 struct drm_crtc;
 
+/*
+ * VBLANK helpers
+ */
+
+void drm_crtc_vblank_atomic_flush(struct drm_crtc *crtc,
+				  struct drm_atomic_state *state);
+void drm_crtc_vblank_atomic_enable(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state);
+void drm_crtc_vblank_atomic_disable(struct drm_crtc *crtc,
+				    struct drm_atomic_state *crtc_state);
+
+/**
+ * DRM_CRTC_HELPER_VBLANK_FUNCS - Default implementation for VBLANK helpers
+ *
+ * This macro initializes struct &drm_crtc_helper_funcs to default helpers
+ * for VBLANK handling.
+ */
+#define DRM_CRTC_HELPER_VBLANK_FUNCS \
+	.atomic_flush = drm_crtc_vblank_atomic_flush, \
+	.atomic_enable = drm_crtc_vblank_atomic_enable, \
+	.atomic_disable = drm_crtc_vblank_atomic_disable
+
 /*
  * VBLANK timer
  */
-- 
2.50.1