Date:   Mon, 31 Jul 2017 22:03:06 -0700
From:   Keith Packard <keithp@...thp.com>
To:     linux-kernel@...r.kernel.org, Dave Airlie <airlied@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, Keith Packard <keithp@...thp.com>
Subject: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls [v2]

These provide crtc-id based functions instead of pipe-number, while
also offering higher resolution time (ns) and wider frame count (64)
as required by the Vulkan API.

v2:

 * Check for DRIVER_MODESET in new crtc-based vblank ioctls

	Failing to check this will oops the driver.

 * Ensure vblank interupt is running in crtc_get_sequence ioctl

	The sequence and timing values are not correct while the
	interrupt is off, so make sure it's running before asking for
	them.

 * Short-circuit get_sequence if the counter is enabled and accurate

	Steal the idea from the code in wait_vblank to avoid the
	expense of drm_vblank_get/put

 * Return active state of crtc in crtc_get_sequence ioctl

	Might be useful for applications that aren't in charge of
	modesetting?

 * Use drm_crtc_vblank_get/put in new crtc-based vblank sequence ioctls

	Daniel Vetter prefers these over the old drm_vblank_put/get
	APIs.

 * Return s64 ns instead of u64 in new sequence event

Suggested-by:  Daniel Vetter <daniel@...ll.ch>
Suggested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Signed-off-by: Keith Packard <keithp@...thp.com>
---
 drivers/gpu/drm/drm_internal.h |   6 ++
 drivers/gpu/drm/drm_ioctl.c    |   2 +
 drivers/gpu/drm/drm_vblank.c   | 173 +++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_vblank.h       |   1 +
 include/uapi/drm/drm.h         |  32 ++++++++
 5 files changed, 214 insertions(+)

diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 5cecc974d2f9..b68a193b7907 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -65,6 +65,12 @@ int drm_legacy_irq_control(struct drm_device *dev, void *data,
 int drm_legacy_modeset_ctl(struct drm_device *dev, void *data,
 			   struct drm_file *file_priv);
 
+int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data,
+				struct drm_file *filp);
+
+int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
+				  struct drm_file *filp);
+
 /* drm_auth.c */
 int drm_getmagic(struct drm_device *dev, void *data,
 		 struct drm_file *file_priv);
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index f1e568176da9..63016cf3e224 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -657,6 +657,8 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, drm_syncobj_fd_to_handle_ioctl,
 		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE, drm_crtc_get_sequence_ioctl, DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE, drm_crtc_queue_sequence_ioctl, DRM_UNLOCKED),
 };
 
 #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 7e7119a5ada3..69b8c92cdd3a 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -812,6 +812,11 @@ static void send_vblank_event(struct drm_device *dev,
 		e->event.vbl.tv_sec = tv.tv_sec;
 		e->event.vbl.tv_usec = tv.tv_usec;
 		break;
+	case DRM_EVENT_CRTC_SEQUENCE:
+		if (seq)
+			e->event.seq.sequence = seq;
+		e->event.seq.time_ns = ktime_to_ns(now);
+		break;
 	}
 	trace_drm_vblank_event_delivered(e->base.file_priv, e->pipe, seq);
 	drm_send_event_locked(dev, &e->base);
@@ -1682,3 +1687,171 @@ bool drm_crtc_handle_vblank(struct drm_crtc *crtc)
 	return drm_handle_vblank(crtc->dev, drm_crtc_index(crtc));
 }
 EXPORT_SYMBOL(drm_crtc_handle_vblank);
+
+/*
+ * Get crtc VBLANK count.
+ *
+ * \param dev DRM device
+ * \param data user arguement, pointing to a drm_crtc_get_sequence structure.
+ * \param file_priv drm file private for the user's open file descriptor
+ */
+
+int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data,
+				struct drm_file *file_priv)
+{
+	struct drm_crtc *crtc;
+	struct drm_vblank_crtc *vblank;
+	int pipe;
+	struct drm_crtc_get_sequence *get_seq = data;
+	ktime_t now;
+	bool vblank_enabled;
+	int ret;
+
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return -EINVAL;
+
+	if (!dev->irq_enabled)
+		return -EINVAL;
+
+	crtc = drm_crtc_find(dev, get_seq->crtc_id);
+	if (!crtc)
+		return -ENOENT;
+
+	pipe = drm_crtc_index(crtc);
+
+	vblank = &dev->vblank[pipe];
+	vblank_enabled = dev->vblank_disable_immediate && READ_ONCE(vblank->enabled);
+
+	if (!vblank_enabled) {
+		ret = drm_crtc_vblank_get(crtc);
+		if (ret) {
+			DRM_DEBUG("crtc %d failed to acquire vblank counter, %d\n", pipe, ret);
+			return ret;
+		}
+	}
+	drm_modeset_lock(&crtc->mutex, NULL);
+	if (crtc->state)
+		get_seq->active = crtc->state->enable;
+	else
+		get_seq->active = crtc->enabled;
+	drm_modeset_unlock(&crtc->mutex);
+	get_seq->sequence = drm_vblank_count_and_time(dev, pipe, &now);
+	get_seq->sequence_ns = ktime_to_ns(now);
+	if (!vblank_enabled)
+		drm_crtc_vblank_put(crtc);
+	return 0;
+}
+
+/*
+ * Queue a event for VBLANK sequence
+ *
+ * \param dev DRM device
+ * \param data user arguement, pointing to a drm_crtc_queue_sequence structure.
+ * \param file_priv drm file private for the user's open file descriptor
+ */
+
+int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
+				  struct drm_file *file_priv)
+{
+	struct drm_crtc *crtc;
+	struct drm_vblank_crtc *vblank;
+	int pipe;
+	struct drm_crtc_queue_sequence *queue_seq = data;
+	ktime_t now;
+	struct drm_pending_vblank_event *e;
+	u32 flags;
+	u64 seq;
+	u64 req_seq;
+	int ret;
+	unsigned long spin_flags;
+
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return -EINVAL;
+
+	if (!dev->irq_enabled)
+		return -EINVAL;
+
+	crtc = drm_crtc_find(dev, queue_seq->crtc_id);
+	if (!crtc)
+		return -ENOENT;
+
+	flags = queue_seq->flags;
+	/* Check valid flag bits */
+	if (flags & ~(DRM_CRTC_SEQUENCE_RELATIVE|
+		      DRM_CRTC_SEQUENCE_NEXT_ON_MISS|
+		      DRM_CRTC_SEQUENCE_FIRST_PIXEL_OUT))
+		return -EINVAL;
+
+	/* Check for valid signal edge */
+	if (!(flags & DRM_CRTC_SEQUENCE_FIRST_PIXEL_OUT))
+		return -EINVAL;
+
+	pipe = drm_crtc_index(crtc);
+
+	vblank = &dev->vblank[pipe];
+
+	e = kzalloc(sizeof(*e), GFP_KERNEL);
+	if (e == NULL)
+		return -ENOMEM;
+
+	ret = drm_crtc_vblank_get(crtc);
+	if (ret) {
+		DRM_DEBUG("crtc %d failed to acquire vblank counter, %d\n", pipe, ret);
+		goto err_free;
+	}
+
+	seq = drm_vblank_count_and_time(dev, pipe, &now);
+	req_seq = queue_seq->sequence;
+
+	if (flags & DRM_CRTC_SEQUENCE_RELATIVE)
+		req_seq += seq;
+
+	if ((flags & DRM_CRTC_SEQUENCE_NEXT_ON_MISS) && vblank_passed(seq, req_seq))
+		req_seq = seq + 1;
+
+	e->pipe = pipe;
+	e->event.base.type = DRM_EVENT_CRTC_SEQUENCE;
+	e->event.base.length = sizeof(e->event.seq);
+	e->event.seq.user_data = queue_seq->user_data;
+
+	spin_lock_irqsave(&dev->event_lock, spin_flags);
+
+	/*
+	 * drm_crtc_vblank_off() might have been called after we called
+	 * drm_crtc_vblank_get(). drm_crtc_vblank_off() holds event_lock around the
+	 * vblank disable, so no need for further locking.  The reference from
+	 * drm_crtc_vblank_get() protects against vblank disable from another source.
+	 */
+	if (!READ_ONCE(vblank->enabled)) {
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+
+	ret = drm_event_reserve_init_locked(dev, file_priv, &e->base,
+					    &e->event.base);
+
+	if (ret)
+		goto err_unlock;
+
+	e->sequence = req_seq;
+
+	if (vblank_passed(seq, req_seq)) {
+		drm_crtc_vblank_put(crtc);
+		send_vblank_event(dev, e, seq, now);
+		queue_seq->sequence = seq;
+	} else {
+		/* drm_handle_vblank_events will call drm_vblank_put */
+		list_add_tail(&e->base.link, &dev->vblank_event_list);
+		queue_seq->sequence = req_seq;
+	}
+
+	spin_unlock_irqrestore(&dev->event_lock, spin_flags);
+	return 0;
+
+err_unlock:
+	spin_unlock_irqrestore(&dev->event_lock, spin_flags);
+	drm_crtc_vblank_put(crtc);
+err_free:
+	kfree(e);
+	return ret;
+}
diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index 3013c55aec1d..2029313bce89 100644
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -57,6 +57,7 @@ struct drm_pending_vblank_event {
 	union {
 		struct drm_event base;
 		struct drm_event_vblank vbl;
+		struct drm_event_crtc_sequence seq;
 	} event;
 };
 
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 101593ab10ac..25478560512a 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -718,6 +718,27 @@ struct drm_syncobj_handle {
 	__u32 pad;
 };
 
+/* Query current scanout sequence number */
+struct drm_crtc_get_sequence {
+	__u32 crtc_id;		/* requested crtc_id */
+	__u32 active;		/* return: crtc output is active */
+	__u64 sequence;		/* return: most recent vblank sequence */
+	__s64 sequence_ns;	/* return: most recent vblank time */
+};
+
+/* Queue event to be delivered at specified sequence */
+
+#define DRM_CRTC_SEQUENCE_RELATIVE		0x00000001	/* sequence is relative to current */
+#define DRM_CRTC_SEQUENCE_NEXT_ON_MISS		0x00000002	/* Use next sequence if we've missed */
+#define DRM_CRTC_SEQUENCE_FIRST_PIXEL_OUT	0x00000004	/* Signal when first pixel is displayed */
+
+struct drm_crtc_queue_sequence {
+	__u32 crtc_id;
+	__u32 flags;
+	__u64 sequence;		/* on input, target sequence. on output, actual sequence */
+	__u64 user_data;	/* user data passed to event */
+};
+
 #if defined(__cplusplus)
 }
 #endif
@@ -800,6 +821,9 @@ extern "C" {
 
 #define DRM_IOCTL_WAIT_VBLANK		DRM_IOWR(0x3a, union drm_wait_vblank)
 
+#define DRM_IOCTL_CRTC_GET_SEQUENCE	DRM_IOWR(0x3b, struct drm_crtc_get_sequence)
+#define DRM_IOCTL_CRTC_QUEUE_SEQUENCE	DRM_IOWR(0x3c, struct drm_crtc_queue_sequence)
+
 #define DRM_IOCTL_UPDATE_DRAW		DRM_IOW(0x3f, struct drm_update_draw)
 
 #define DRM_IOCTL_MODE_GETRESOURCES	DRM_IOWR(0xA0, struct drm_mode_card_res)
@@ -871,6 +895,7 @@ struct drm_event {
 
 #define DRM_EVENT_VBLANK 0x01
 #define DRM_EVENT_FLIP_COMPLETE 0x02
+#define DRM_EVENT_CRTC_SEQUENCE	0x03
 
 struct drm_event_vblank {
 	struct drm_event base;
@@ -881,6 +906,13 @@ struct drm_event_vblank {
 	__u32 crtc_id; /* 0 on older kernels that do not support this */
 };
 
+struct drm_event_crtc_sequence {
+	struct drm_event	base;
+	__u64			user_data;
+	__s64			time_ns;
+	__u64			sequence;
+};
+
 /* typedef area */
 #ifndef __KERNEL__
 typedef struct drm_clip_rect drm_clip_rect_t;
-- 
2.13.3

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