[PATCH 3/6] drm/simpledrm: Use vblank timer

[Thomas Zimmermann]

Simpledrm hardware does not provide vblank interrupts. Use a vblank
timer to simulate the inerrup tin software. Rate-limits the display's
update frequency to the display-mode settings.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/sysfb/simpledrm.c | 81 +++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/drivers/gpu/drm/sysfb/simpledrm.c b/drivers/gpu/drm/sysfb/simpledrm.c
index a1c3119330de..b9766129f564 100644
--- a/drivers/gpu/drm/sysfb/simpledrm.c
+++ b/drivers/gpu/drm/sysfb/simpledrm.c
@@ -26,6 +26,8 @@
 #include <drm/drm_managed.h>
 #include <drm/drm_modeset_helper_vtables.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_vblank_timer.h>
 
 #include "drm_sysfb_helper.h"
 
@@ -229,11 +231,17 @@ struct simpledrm_device {
 	/* modesetting */
 	u32 formats[DRM_SYSFB_PLANE_NFORMATS(1)];
 	struct drm_plane primary_plane;
+	struct drm_vblank_timer vtimer;
 	struct drm_crtc crtc;
 	struct drm_encoder encoder;
 	struct drm_connector connector;
 };
 
+static struct simpledrm_device *to_simpledrm_device(struct drm_device *dev)
+{
+	return container_of(to_drm_sysfb_device(dev), struct simpledrm_device, sysfb);
+}
+
 /*
  * Hardware
  */
@@ -564,13 +572,79 @@ static const struct drm_plane_funcs simpledrm_primary_plane_funcs = {
 	.destroy = drm_plane_cleanup,
 };
 
+static void simpledrm_crtc_helper_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);
+}
+
+static void simpledrm_crtc_helper_atomic_enable(struct drm_crtc *crtc,
+						struct drm_atomic_state *state)
+{
+	drm_crtc_vblank_on(crtc);
+}
+
+static void simpledrm_crtc_helper_atomic_disable(struct drm_crtc *crtc,
+						 struct drm_atomic_state *state)
+{
+	drm_crtc_vblank_off(crtc);
+}
+
 static const struct drm_crtc_helper_funcs simpledrm_crtc_helper_funcs = {
 	DRM_SYSFB_CRTC_HELPER_FUNCS,
+	.atomic_flush = simpledrm_crtc_helper_atomic_flush,
+	.atomic_enable = simpledrm_crtc_helper_atomic_enable,
+	.atomic_disable = simpledrm_crtc_helper_atomic_disable,
 };
 
+static int simpledrm_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+	struct simpledrm_device *sdev = to_simpledrm_device(crtc->dev);
+
+	drm_vblank_timer_start(&sdev->vtimer);
+
+	return 0;
+}
+
+static void simpledrm_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+	struct simpledrm_device *sdev = to_simpledrm_device(crtc->dev);
+
+	drm_vblank_timer_cancel(&sdev->vtimer);
+}
+
+static bool simpledrm_crtc_get_vblank_timestamp(struct drm_crtc *crtc,
+						int *max_error, ktime_t *vblank_time,
+						bool in_vblank_irq)
+{
+	struct simpledrm_device *sdev = to_simpledrm_device(crtc->dev);
+
+	return drm_vblank_timer_get_vblank_timestamp(&sdev->vtimer, max_error,
+						     vblank_time, in_vblank_irq);
+}
+
 static const struct drm_crtc_funcs simpledrm_crtc_funcs = {
 	DRM_SYSFB_CRTC_FUNCS,
 	.destroy = drm_crtc_cleanup,
+	.enable_vblank = simpledrm_crtc_enable_vblank,
+	.disable_vblank = simpledrm_crtc_disable_vblank,
+	.get_vblank_timestamp = simpledrm_crtc_get_vblank_timestamp,
 };
 
 static const struct drm_encoder_funcs simpledrm_encoder_funcs = {
@@ -611,6 +685,7 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 	struct drm_crtc *crtc;
 	struct drm_encoder *encoder;
 	struct drm_connector *connector;
+	struct drm_vblank_timer *vtimer;
 	unsigned long max_width, max_height;
 	size_t nformats;
 	int ret;
@@ -812,6 +887,12 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 	if (ret)
 		return ERR_PTR(ret);
 
+	/* Vertical blanking */
+
+	vtimer = &sdev->vtimer;
+	drmm_vblank_timer_init(vtimer, crtc, NULL);
+	drm_vblank_init(dev, 1);
+
 	drm_mode_config_reset(dev);
 
 	return sdev;
-- 
2.49.0