[PATCH 1/2] drm/mediatek: Only block updates to CRTCs that have a pending update

[Bibby Hsieh]

Currently we use a single mutex to allow only a single atomic
update at a time. In truth, though, we really only want to
ensure that only a single atomic update is allowed per CRTC.

In other words, for each atomic update, we only block if there
is a pending update for the CRTCs involved, and don't block if
there are only pending updates for other CRTCs.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")

Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c |  14 +-
 drivers/gpu/drm/mediatek/mtk_drm_drv.c  | 182 +++++++++++++++++++++---
 drivers/gpu/drm/mediatek/mtk_drm_drv.h  |  12 +-
 3 files changed, 184 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index b55970a2869d..7697b40baac0 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -5,6 +5,7 @@
 
 #include <asm/barrier.h>
 #include <drm/drmP.h>
+#include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_probe_helper.h>
@@ -45,6 +46,8 @@ struct mtk_drm_crtc {
 	struct mtk_disp_mutex		*mutex;
 	unsigned int			ddp_comp_nr;
 	struct mtk_ddp_comp		**ddp_comp;
+
+	struct drm_crtc_state		*old_crtc_state;
 };
 
 struct mtk_crtc_state {
@@ -343,6 +346,7 @@ static void mtk_crtc_ddp_hw_fini(struct mtk_drm_crtc *mtk_crtc)
 static void mtk_crtc_ddp_config(struct drm_crtc *crtc)
 {
 	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
+	struct drm_atomic_state *atomic_state = mtk_crtc->old_crtc_state->state;
 	struct mtk_crtc_state *state = to_mtk_crtc_state(mtk_crtc->base.state);
 	struct mtk_ddp_comp *comp = mtk_crtc->ddp_comp[0];
 	unsigned int i;
@@ -382,6 +386,7 @@ static void mtk_crtc_ddp_config(struct drm_crtc *crtc)
 			}
 		}
 		mtk_crtc->pending_planes = false;
+		mtk_atomic_state_put_queue(atomic_state);
 	}
 }
 
@@ -451,6 +456,7 @@ static void mtk_drm_crtc_atomic_begin(struct drm_crtc *crtc,
 static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
 				      struct drm_crtc_state *old_crtc_state)
 {
+	struct drm_atomic_state *old_atomic_state = old_crtc_state->state;
 	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
 	struct mtk_drm_private *priv = crtc->dev->dev_private;
 	unsigned int pending_planes = 0;
@@ -469,8 +475,13 @@ static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
 			pending_planes |= BIT(i);
 		}
 	}
-	if (pending_planes)
+
+	if (pending_planes) {
 		mtk_crtc->pending_planes = true;
+		drm_atomic_state_get(old_atomic_state);
+		mtk_crtc->old_crtc_state = old_crtc_state;
+	}
+
 	if (crtc->state->color_mgmt_changed)
 		for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
 			mtk_ddp_gamma_set(mtk_crtc->ddp_comp[i], crtc->state);
@@ -526,6 +537,7 @@ static int mtk_drm_crtc_init(struct drm_device *drm,
 
 void mtk_crtc_ddp_irq(struct drm_crtc *crtc, struct mtk_ddp_comp *comp)
 {
+
 	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
 	struct mtk_drm_private *priv = crtc->dev->dev_private;
 
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index c0928b69dc43..b0308a3a7483 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -31,11 +31,120 @@
 #define DRIVER_MAJOR 1
 #define DRIVER_MINOR 0
 
-static void mtk_atomic_schedule(struct mtk_drm_private *private,
+struct mtk_atomic_state {
+	struct drm_atomic_state base;
+	struct list_head list;
+	struct work_struct work;
+};
+
+static inline struct mtk_atomic_state *to_mtk_state(struct drm_atomic_state *s)
+{
+	return container_of(s, struct mtk_atomic_state, base);
+}
+
+void mtk_atomic_state_put_queue(struct drm_atomic_state *state)
+{
+	struct drm_device *drm = state->dev;
+	struct mtk_drm_private *mtk_drm = drm->dev_private;
+	struct mtk_atomic_state *mtk_state = to_mtk_state(state);
+	unsigned long flags;
+
+	spin_lock_irqsave(&mtk_drm->unreference.lock, flags);
+	list_add_tail(&mtk_state->list, &mtk_drm->unreference.list);
+	spin_unlock_irqrestore(&mtk_drm->unreference.lock, flags);
+
+	schedule_work(&mtk_drm->unreference.work);
+}
+
+static uint32_t mtk_atomic_crtc_mask(struct drm_device *drm,
+				     struct drm_atomic_state *state)
+{
+	uint32_t crtc_mask;
+	int i;
+
+	for (i = 0, crtc_mask = 0; i < drm->mode_config.num_crtc; i++) {
+		struct drm_crtc *crtc = state->crtcs[i].ptr;
+
+		if (crtc)
+			crtc_mask |= (1 << drm_crtc_index(crtc));
+	}
+
+	return crtc_mask;
+}
+
+/*
+ * Block until specified crtcs are no longer pending update, and atomically
+ * mark them as pending update.
+ */
+static int mtk_atomic_get_crtcs(struct drm_device *drm,
+				struct drm_atomic_state *state)
+{
+	struct mtk_drm_private *private = drm->dev_private;
+	uint32_t crtc_mask;
+	int ret;
+
+	crtc_mask = mtk_atomic_crtc_mask(drm, state);
+
+	/*
+	 * Wait for all pending updates to complete for the set of crtcs being
+	 * changed in this atomic commit
+	 */
+	spin_lock(&private->commit.crtcs_event.lock);
+	ret = wait_event_interruptible_locked(private->commit.crtcs_event,
+			!(private->commit.crtcs & crtc_mask));
+	if (ret == 0)
+		private->commit.crtcs |= crtc_mask;
+	spin_unlock(&private->commit.crtcs_event.lock);
+
+	return ret;
+}
+
+/*
+ * Mark specified crtcs as no longer pending update.
+ */
+static void mtk_atomic_put_crtcs(struct drm_device *drm,
+				 struct drm_atomic_state *state)
+{
+	struct mtk_drm_private *private = drm->dev_private;
+	uint32_t crtc_mask;
+
+	crtc_mask = mtk_atomic_crtc_mask(drm, state);
+
+	spin_lock(&private->commit.crtcs_event.lock);
+	private->commit.crtcs &= ~crtc_mask;
+	wake_up_all_locked(&private->commit.crtcs_event);
+	spin_unlock(&private->commit.crtcs_event.lock);
+}
+
+static void mtk_unreference_work(struct work_struct *work)
+{
+	struct mtk_drm_private *mtk_drm = container_of(work,
+			struct mtk_drm_private, unreference.work);
+	unsigned long flags;
+	struct mtk_atomic_state *state, *tmp;
+
+	/*
+	 * framebuffers cannot be unreferenced in atomic context.
+	 * Therefore, only hold the spinlock when iterating unreference_list,
+	 * and drop it when doing the unreference.
+	 */
+	spin_lock_irqsave(&mtk_drm->unreference.lock, flags);
+	list_for_each_entry_safe(state, tmp, &mtk_drm->unreference.list, list) {
+		list_del(&state->list);
+		spin_unlock_irqrestore(&mtk_drm->unreference.lock, flags);
+		drm_atomic_state_put(&state->base);
+		spin_lock_irqsave(&mtk_drm->unreference.lock, flags);
+	}
+	spin_unlock_irqrestore(&mtk_drm->unreference.lock, flags);
+}
+
+
+static void mtk_atomic_schedule(struct drm_device *drm,
 				struct drm_atomic_state *state)
 {
-	private->commit.state = state;
-	schedule_work(&private->commit.work);
+	struct mtk_atomic_state *mtk_state = to_mtk_state(state);
+
+	schedule_work(&mtk_state->work);
 }
 
 static void mtk_atomic_wait_for_fences(struct drm_atomic_state *state)
@@ -48,13 +157,10 @@ static void mtk_atomic_wait_for_fences(struct drm_atomic_state *state)
 		mtk_fb_wait(new_plane_state->fb);
 }
 
-static void mtk_atomic_complete(struct mtk_drm_private *private,
+static void mtk_atomic_complete(struct drm_device *drm,
 				struct drm_atomic_state *state)
 {
-	struct drm_device *drm = private->drm;
-
 	mtk_atomic_wait_for_fences(state);
-
 	/*
 	 * Mediatek drm supports runtime PM, so plane registers cannot be
 	 * written when their crtc is disabled.
@@ -77,53 +183,86 @@ static void mtk_atomic_complete(struct mtk_drm_private *private,
 	drm_atomic_helper_wait_for_vblanks(drm, state);
 
 	drm_atomic_helper_cleanup_planes(drm, state);
+	mtk_atomic_put_crtcs(drm, state);
+
 	drm_atomic_state_put(state);
 }
 
 static void mtk_atomic_work(struct work_struct *work)
 {
-	struct mtk_drm_private *private = container_of(work,
-			struct mtk_drm_private, commit.work);
+	struct mtk_atomic_state *mtk_state = container_of(work,
+			struct mtk_atomic_state, work);
+	struct drm_atomic_state *state = &mtk_state->base;
+	struct drm_device *drm = state->dev;
 
-	mtk_atomic_complete(private, private->commit.state);
+	mtk_atomic_complete(drm, state);
 }
 
 static int mtk_atomic_commit(struct drm_device *drm,
 			     struct drm_atomic_state *state,
 			     bool async)
 {
-	struct mtk_drm_private *private = drm->dev_private;
 	int ret;
 
 	ret = drm_atomic_helper_prepare_planes(drm, state);
 	if (ret)
 		return ret;
 
-	mutex_lock(&private->commit.lock);
-	flush_work(&private->commit.work);
+	ret = mtk_atomic_get_crtcs(drm, state);
+	if (ret) {
+		drm_atomic_helper_cleanup_planes(drm, state);
+		return ret;
+	}
 
 	ret = drm_atomic_helper_swap_state(state, true);
 	if (ret) {
-		mutex_unlock(&private->commit.lock);
 		drm_atomic_helper_cleanup_planes(drm, state);
 		return ret;
 	}
 
 	drm_atomic_state_get(state);
 	if (async)
-		mtk_atomic_schedule(private, state);
+		mtk_atomic_schedule(drm, state);
 	else
-		mtk_atomic_complete(private, state);
-
-	mutex_unlock(&private->commit.lock);
+		mtk_atomic_complete(drm, state);
 
 	return 0;
 }
 
+static struct drm_atomic_state *mtk_drm_atomic_state_alloc(
+		struct drm_device *dev)
+{
+	struct mtk_atomic_state *mtk_state;
+
+	mtk_state = kzalloc(sizeof(*mtk_state), GFP_KERNEL);
+	if (!mtk_state)
+		return NULL;
+
+	if (drm_atomic_state_init(dev, &mtk_state->base) < 0) {
+		kfree(mtk_state);
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&mtk_state->list);
+	INIT_WORK(&mtk_state->work, mtk_atomic_work);
+
+	return &mtk_state->base;
+}
+
+static void mtk_drm_atomic_state_free(struct drm_atomic_state *state)
+{
+	struct mtk_atomic_state *mtk_state = to_mtk_state(state);
+
+	drm_atomic_state_default_release(state);
+	kfree(mtk_state);
+}
+
 static const struct drm_mode_config_funcs mtk_drm_mode_config_funcs = {
 	.fb_create = mtk_drm_mode_fb_create,
 	.atomic_check = drm_atomic_helper_check,
 	.atomic_commit = mtk_atomic_commit,
+	.atomic_state_alloc = mtk_drm_atomic_state_alloc,
+	.atomic_state_free = mtk_drm_atomic_state_free
 };
 
 static const enum mtk_ddp_comp_id mt2701_mtk_ddp_main[] = {
@@ -319,6 +458,11 @@ static int mtk_drm_kms_init(struct drm_device *drm)
 	drm_kms_helper_poll_init(drm);
 	drm_mode_config_reset(drm);
 
+	INIT_WORK(&private->unreference.work, mtk_unreference_work);
+	INIT_LIST_HEAD(&private->unreference.list);
+	spin_lock_init(&private->unreference.lock);
+	init_waitqueue_head(&private->commit.crtcs_event);
+
 	return 0;
 
 err_component_unbind:
@@ -504,8 +648,6 @@ static int mtk_drm_probe(struct platform_device *pdev)
 	if (!private)
 		return -ENOMEM;
 
-	mutex_init(&private->commit.lock);
-	INIT_WORK(&private->commit.work, mtk_atomic_work);
 	private->data = of_device_get_match_data(dev);
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.h b/drivers/gpu/drm/mediatek/mtk_drm_drv.h
index 823ba4081c18..0934f83b860d 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.h
@@ -48,12 +48,16 @@ struct mtk_drm_private {
 	const struct mtk_mmsys_driver_data *data;
 
 	struct {
-		struct drm_atomic_state *state;
-		struct work_struct work;
-		struct mutex lock;
+		uint32_t crtcs;
+		wait_queue_head_t crtcs_event;
 	} commit;
 
 	struct drm_atomic_state *suspend_state;
+	struct {
+		struct work_struct	work;
+		struct list_head	list;
+		spinlock_t		lock;
+	} unreference;
 };
 
 extern struct platform_driver mtk_ddp_driver;
@@ -64,4 +68,6 @@ extern struct platform_driver mtk_dpi_driver;
 extern struct platform_driver mtk_dsi_driver;
 extern struct platform_driver mtk_mipi_tx_driver;
 
+void mtk_atomic_state_put_queue(struct drm_atomic_state *state);
+
 #endif /* MTK_DRM_DRV_H */
-- 
2.18.0