drm/tegra: Implement buffer object cache

This cache is used to avoid mapping and unmapping buffer objects
unnecessarily. Mappings are cached per client and stay hot until
the buffer object is destroyed.

Signed-off-by: Thierry Reding <treding@nvidia.com>

4 files changed, 84 insertions, 2 deletions

diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
index 218e3718fd68..0b67d894470d 100644
--- a/drivers/gpu/host1x/bus.c
+++ b/drivers/gpu/host1x/bus.c
@@ -742,6 +742,7 @@ EXPORT_SYMBOL(host1x_driver_unregister);
  */
 void __host1x_client_init(struct host1x_client *client, struct lock_class_key *key)
 {
+	host1x_bo_cache_init(&client->cache);
 	INIT_LIST_HEAD(&client->list);
 	__mutex_init(&client->lock, "host1x client lock", key);
 	client->usecount = 0;
@@ -830,6 +831,8 @@ int host1x_client_unregister(struct host1x_client *client)
 
 	mutex_unlock(&clients_lock);
 
+	host1x_bo_cache_destroy(&client->cache);
+
 	return 0;
 }
 EXPORT_SYMBOL(host1x_client_unregister);
@@ -904,3 +907,78 @@ unlock:
 	return err;
 }
 EXPORT_SYMBOL(host1x_client_resume);
+
+struct host1x_bo_mapping *host1x_bo_pin(struct device *dev, struct host1x_bo *bo,
+					enum dma_data_direction dir,
+					struct host1x_bo_cache *cache)
+{
+	struct host1x_bo_mapping *mapping;
+
+	if (cache) {
+		mutex_lock(&cache->lock);
+
+		list_for_each_entry(mapping, &cache->mappings, entry) {
+			if (mapping->bo == bo && mapping->direction == dir) {
+				kref_get(&mapping->ref);
+				goto unlock;
+			}
+		}
+	}
+
+	mapping = bo->ops->pin(dev, bo, dir);
+	if (IS_ERR(mapping))
+		goto unlock;
+
+	spin_lock(&mapping->bo->lock);
+	list_add_tail(&mapping->list, &bo->mappings);
+	spin_unlock(&mapping->bo->lock);
+
+	if (cache) {
+		INIT_LIST_HEAD(&mapping->entry);
+		mapping->cache = cache;
+
+		list_add_tail(&mapping->entry, &cache->mappings);
+
+		/* bump reference count to track the copy in the cache */
+		kref_get(&mapping->ref);
+	}
+
+unlock:
+	if (cache)
+		mutex_unlock(&cache->lock);
+
+	return mapping;
+}
+EXPORT_SYMBOL(host1x_bo_pin);
+
+static void __host1x_bo_unpin(struct kref *ref)
+{
+	struct host1x_bo_mapping *mapping = to_host1x_bo_mapping(ref);
+
+	/*
+	 * When the last reference of the mapping goes away, make sure to remove the mapping from
+	 * the cache.
+	 */
+	if (mapping->cache)
+		list_del(&mapping->entry);
+
+	spin_lock(&mapping->bo->lock);
+	list_del(&mapping->list);
+	spin_unlock(&mapping->bo->lock);
+
+	mapping->bo->ops->unpin(mapping);
+}
+
+void host1x_bo_unpin(struct host1x_bo_mapping *mapping)
+{
+	struct host1x_bo_cache *cache = mapping->cache;
+
+	if (cache)
+		mutex_lock(&cache->lock);
+
+	kref_put(&mapping->ref, __host1x_bo_unpin);
+
+	if (cache)
+		mutex_unlock(&cache->lock);
+}
+EXPORT_SYMBOL(host1x_bo_unpin);
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index fbb6447b8659..85eb3d19bbdb 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -386,6 +386,7 @@ static int host1x_probe(struct platform_device *pdev)
 	if (syncpt_irq < 0)
 		return syncpt_irq;
 
+	host1x_bo_cache_init(&host->cache);
 	mutex_init(&host->devices_lock);
 	INIT_LIST_HEAD(&host->devices);
 	INIT_LIST_HEAD(&host->list);
@@ -512,6 +513,7 @@ static int host1x_remove(struct platform_device *pdev)
 	reset_control_assert(host->rst);
 	clk_disable_unprepare(host->clk);
 	host1x_iommu_exit(host);
+	host1x_bo_cache_destroy(&host->cache);
 
 	return 0;
 }
diff --git a/drivers/gpu/host1x/dev.h b/drivers/gpu/host1x/dev.h
index fa6d4bc46e98..5b7fdea5d169 100644
--- a/drivers/gpu/host1x/dev.h
+++ b/drivers/gpu/host1x/dev.h
@@ -149,6 +149,8 @@ struct host1x {
 	struct list_head list;
 
 	struct device_dma_parameters dma_parms;
+
+	struct host1x_bo_cache cache;
 };
 
 void host1x_hypervisor_writel(struct host1x *host1x, u32 r, u32 v);
diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c
index 64bcc3d83efc..5e8c183167b7 100644
--- a/drivers/gpu/host1x/job.c
+++ b/drivers/gpu/host1x/job.c
@@ -175,7 +175,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
 			goto unpin;
 		}
 
-		map = host1x_bo_pin(dev, bo, direction);
+		map = host1x_bo_pin(dev, bo, direction, &client->cache);
 		if (IS_ERR(map)) {
 			err = PTR_ERR(map);
 			goto unpin;
@@ -222,7 +222,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
 			goto unpin;
 		}
 
-		map = host1x_bo_pin(host->dev, g->bo, DMA_TO_DEVICE);
+		map = host1x_bo_pin(host->dev, g->bo, DMA_TO_DEVICE, &host->cache);
 		if (IS_ERR(map)) {
 			err = PTR_ERR(map);
 			goto unpin;