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 <djku...@chromium.org>
Signed-off-by: Bibby Hsieh <bibby.hs...@mediatek.com>
---
 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

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