[PATCH v6 3/9] v4l: vsp1: Provide a body pool

Kieran Bingham
2018-02-28T20:52:56Z

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 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>

---
v4:
- Provide comment explaining extra allocation on body pool
highlighting area for optimisation later.

v3:
- s/fragment/body/, s/fragments/bodies/
- qty -> num_bodies
- indentation fix
- s/vsp1_dl_body_pool_{alloc,free}/vsp1_dl_body_pool_{create,destroy}/'
- Add kerneldoc to non-static functions

v2:
- assign dlb->dma correctly

drivers/media/platform/vsp1/vsp1_dl.c | 163 +++++++++++++++++++++++++++-
drivers/media/platform/vsp1/vsp1_dl.h | 8 +-
2 files changed, 171 insertions(+)

diff --git a/drivers/media/platform/vsp1/vsp1_dl.c b/drivers/media/platform/vsp1/vsp1_dl.c
index 59fe80bf6e9d..87bc4acf8c9e 100644
--- a/drivers/media/platform/vsp1/vsp1_dl.c
+++ b/drivers/media/platform/vsp1/vsp1_dl.c
@@ -45,6 +45,8 @@ 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
@@ -54,6 +56,9 @@ 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;
@@ -65,6 +70,30 @@ struct vsp1_dl_body {
};

/**
+ * 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 pool and 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
* @dlm: the display list manager
@@ -105,6 +134,7 @@ 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
*/
@@ -120,6 +150,8 @@ 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;
};
@@ -128,6 +160,137 @@ 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 quantity of bodies to allocate
+ * @num_entries: The maximum number of entries that the 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.
+ *
+ * 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 allocation 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
diff --git a/drivers/media/platform/vsp1/vsp1_dl.h b/drivers/media/platform/vsp1/vsp1_dl.h
index d4f7695c4ed3..785b88472375 100644
--- a/drivers/media/platform/vsp1/vsp1_dl.h
+++ b/drivers/media/platform/vsp1/vsp1_dl.h
@@ -17,6 +17,7 @@

struct vsp1_device;
struct vsp1_dl_body;
+struct vsp1_dl_body_pool;
struct vsp1_dl_list;
struct vsp1_dl_manager;

@@ -34,6 +35,13 @@ 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);

+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);
--
git-series 0.9.1