media: vsp1: Provide a body pool

Each display list allocates a body to store register values in a dma
accessible buffer from a dma_alloc_wc() allocation. Each of these
results in an entry in the IOMMU TLB, and a large number of display list
allocations adds pressure to this resource.

Reduce TLB pressure on the IPMMUs by allocating multiple display list
bodies in a single allocation, and providing these to the display list
through a 'body pool'. A pool can be allocated by the display list
manager or entities which require their own body allocations.
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/vsp1/vsp1_dl.c

@@ -41,6 +41,8 @@ struct vsp1_dl_entry {
 /**
  * struct vsp1_dl_body - Display list body
  * @list: entry in the display list list of bodies
+ * @free: entry in the pool free body list
+ * @pool: pool to which this body belongs
  * @vsp1: the VSP1 device
  * @entries: array of entries
  * @dma: DMA address of the entries
@@ -50,6 +52,9 @@ struct vsp1_dl_entry {
  */
 struct vsp1_dl_body {
 	struct list_head list;
+	struct list_head free;
+
+	struct vsp1_dl_body_pool *pool;
 	struct vsp1_device *vsp1;
 
 	struct vsp1_dl_entry *entries;
@@ -60,6 +65,30 @@ struct vsp1_dl_body {
 	unsigned int max_entries;
 };
 
+/**
+ * struct vsp1_dl_body_pool - display list body pool
+ * @dma: DMA address of the entries
+ * @size: size of the full DMA memory pool in bytes
+ * @mem: CPU memory pointer for the pool
+ * @bodies: Array of DLB structures for the pool
+ * @free: List of free DLB entries
+ * @lock: Protects the free list
+ * @vsp1: the VSP1 device
+ */
+struct vsp1_dl_body_pool {
+	/* DMA allocation */
+	dma_addr_t dma;
+	size_t size;
+	void *mem;
+
+	/* Body management */
+	struct vsp1_dl_body *bodies;
+	struct list_head free;
+	spinlock_t lock;
+
+	struct vsp1_device *vsp1;
+};
+
 /**
  * struct vsp1_dl_list - Display list
  * @list: entry in the display list manager lists
@@ -104,6 +133,7 @@ enum vsp1_dl_mode {
  * @active: list currently being processed (loaded) by hardware
  * @queued: list queued to the hardware (written to the DL registers)
  * @pending: list waiting to be queued to the hardware
+ * @pool: body pool for the display list bodies
  * @gc_work: bodies garbage collector work struct
  * @gc_bodies: array of display list bodies waiting to be freed
  */
@@ -119,6 +149,8 @@ struct vsp1_dl_manager {
 	struct vsp1_dl_list *queued;
 	struct vsp1_dl_list *pending;
 
+	struct vsp1_dl_body_pool *pool;
+
 	struct work_struct gc_work;
 	struct list_head gc_bodies;
 };
@@ -127,6 +159,137 @@ struct vsp1_dl_manager {
  * Display List Body Management
  */
 
+/**
+ * vsp1_dl_body_pool_create - Create a pool of bodies from a single allocation
+ * @vsp1: The VSP1 device
+ * @num_bodies: The number of bodies to allocate
+ * @num_entries: The maximum number of entries that a body can contain
+ * @extra_size: Extra allocation provided for the bodies
+ *
+ * Allocate a pool of display list bodies each with enough memory to contain the
+ * requested number of entries plus the @extra_size.
+ *
+ * Return a pointer to a pool on success or NULL if memory can't be allocated.
+ */
+struct vsp1_dl_body_pool *
+vsp1_dl_body_pool_create(struct vsp1_device *vsp1, unsigned int num_bodies,
+			 unsigned int num_entries, size_t extra_size)
+{
+	struct vsp1_dl_body_pool *pool;
+	size_t dlb_size;
+	unsigned int i;
+
+	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+	if (!pool)
+		return NULL;
+
+	pool->vsp1 = vsp1;
+
+	/*
+	 * TODO: 'extra_size' is only used by vsp1_dlm_create(), to allocate
+	 * extra memory for the display list header. We need only one header per
+	 * display list, not per display list body, thus this allocation is
+	 * extraneous and should be reworked in the future.
+	 */
+	dlb_size = num_entries * sizeof(struct vsp1_dl_entry) + extra_size;
+	pool->size = dlb_size * num_bodies;
+
+	pool->bodies = kcalloc(num_bodies, sizeof(*pool->bodies), GFP_KERNEL);
+	if (!pool->bodies) {
+		kfree(pool);
+		return NULL;
+	}
+
+	pool->mem = dma_alloc_wc(vsp1->bus_master, pool->size, &pool->dma,
+				 GFP_KERNEL);
+	if (!pool->mem) {
+		kfree(pool->bodies);
+		kfree(pool);
+		return NULL;
+	}
+
+	spin_lock_init(&pool->lock);
+	INIT_LIST_HEAD(&pool->free);
+
+	for (i = 0; i < num_bodies; ++i) {
+		struct vsp1_dl_body *dlb = &pool->bodies[i];
+
+		dlb->pool = pool;
+		dlb->max_entries = num_entries;
+
+		dlb->dma = pool->dma + i * dlb_size;
+		dlb->entries = pool->mem + i * dlb_size;
+
+		list_add_tail(&dlb->free, &pool->free);
+	}
+
+	return pool;
+}
+
+/**
+ * vsp1_dl_body_pool_destroy - Release a body pool
+ * @pool: The body pool
+ *
+ * Release all components of a pool allocation.
+ */
+void vsp1_dl_body_pool_destroy(struct vsp1_dl_body_pool *pool)
+{
+	if (!pool)
+		return;
+
+	if (pool->mem)
+		dma_free_wc(pool->vsp1->bus_master, pool->size, pool->mem,
+			    pool->dma);
+
+	kfree(pool->bodies);
+	kfree(pool);
+}
+
+/**
+ * vsp1_dl_body_get - Obtain a body from a pool
+ * @pool: The body pool
+ *
+ * Obtain a body from the pool without blocking.
+ *
+ * Returns a display list body or NULL if there are none available.
+ */
+struct vsp1_dl_body *vsp1_dl_body_get(struct vsp1_dl_body_pool *pool)
+{
+	struct vsp1_dl_body *dlb = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pool->lock, flags);
+
+	if (!list_empty(&pool->free)) {
+		dlb = list_first_entry(&pool->free, struct vsp1_dl_body, free);
+		list_del(&dlb->free);
+	}
+
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	return dlb;
+}
+
+/**
+ * vsp1_dl_body_put - Return a body back to its pool
+ * @dlb: The display list body
+ *
+ * Return a body back to the pool, and reset the num_entries to clear the list.
+ */
+void vsp1_dl_body_put(struct vsp1_dl_body *dlb)
+{
+	unsigned long flags;
+
+	if (!dlb)
+		return;
+
+	dlb->num_entries = 0;
+
+	spin_lock_irqsave(&dlb->pool->lock, flags);
+	list_add_tail(&dlb->free, &dlb->pool->free);
+	spin_unlock_irqrestore(&dlb->pool->lock, flags);
+}
+
 /*
  * Initialize a display list body object and allocate DMA memory for the body
  * data. The display list body object is expected to have been initialized to

drivers/media/platform/vsp1/vsp1_dl.h

@@ -13,6 +13,7 @@
 
 struct vsp1_device;
 struct vsp1_dl_body;
+struct vsp1_dl_body_pool;
 struct vsp1_dl_list;
 struct vsp1_dl_manager;
 
@@ -33,6 +34,13 @@ void vsp1_dl_list_put(struct vsp1_dl_list *dl);
 void vsp1_dl_list_write(struct vsp1_dl_list *dl, u32 reg, u32 data);
 void vsp1_dl_list_commit(struct vsp1_dl_list *dl, bool internal);
 
+struct vsp1_dl_body_pool *
+vsp1_dl_body_pool_create(struct vsp1_device *vsp1, unsigned int num_bodies,
+			 unsigned int num_entries, size_t extra_size);
+void vsp1_dl_body_pool_destroy(struct vsp1_dl_body_pool *pool);
+struct vsp1_dl_body *vsp1_dl_body_get(struct vsp1_dl_body_pool *pool);
+void vsp1_dl_body_put(struct vsp1_dl_body *dlb);
+
 struct vsp1_dl_body *vsp1_dl_body_alloc(struct vsp1_device *vsp1,
 					unsigned int num_entries);
 void vsp1_dl_body_free(struct vsp1_dl_body *dlb);