dmaengine: mv_xor: improve descriptors list handling and reduce locking

This patch change the way free descriptors are marked.

Instead of having a field for descriptor in use, all the descriptors in the
all_slots list are free for use.

This simplify the allocation method and reduce the locking needed.

Signed-off-by: Lior Amsalem <alior@marvell.com>
Reviewed-by: Ofer Heifetz <oferh@marvell.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/mv_xor.h b/drivers/dma/mv_xor.h
index 6b10c8c..b7455b4 100644
--- a/drivers/dma/mv_xor.h
+++ b/drivers/dma/mv_xor.h
@@ -94,11 +94,11 @@
  * @mmr_base: memory mapped register base
  * @idx: the index of the xor channel
  * @chain: device chain view of the descriptors
+ * @free_slots: free slots usable by the channel
+ * @allocated_slots: slots allocated by the driver
  * @completed_slots: slots completed by HW but still need to be acked
  * @device: parent device
  * @common: common dmaengine channel object members
- * @last_used: place holder for allocation to continue from where it left off
- * @all_slots: complete domain of slots usable by the channel
  * @slots_allocated: records the actual size of the descriptor slot pool
  * @irq_tasklet: bottom half where mv_xor_slot_cleanup runs
  * @op_in_desc: new mode of driver, each op is writen to descriptor.
@@ -112,14 +112,14 @@
 	int                     irq;
 	enum dma_transaction_type	current_type;
 	struct list_head	chain;
+	struct list_head	free_slots;
+	struct list_head	allocated_slots;
 	struct list_head	completed_slots;
 	dma_addr_t		dma_desc_pool;
 	void			*dma_desc_pool_virt;
 	size_t                  pool_size;
 	struct dma_device	dmadev;
 	struct dma_chan		dmachan;
-	struct mv_xor_desc_slot	*last_used;
-	struct list_head	all_slots;
 	int			slots_allocated;
 	struct tasklet_struct	irq_tasklet;
 	int                     op_in_desc;
@@ -130,9 +130,7 @@
 
 /**
  * struct mv_xor_desc_slot - software descriptor
- * @slot_node: node on the mv_xor_chan.all_slots list
- * @chain_node: node on the mv_xor_chan.chain list
- * @completed_node: node on the mv_xor_chan.completed_slots list
+ * @node: node on the mv_xor_chan lists
  * @hw_desc: virtual address of the hardware descriptor chain
  * @phys: hardware address of the hardware descriptor chain
  * @slot_used: slot in use or not
@@ -141,12 +139,9 @@
  * @async_tx: support for the async_tx api
  */
 struct mv_xor_desc_slot {
-	struct list_head	slot_node;
-	struct list_head	chain_node;
-	struct list_head	completed_node;
+	struct list_head	node;
 	enum dma_transaction_type	type;
 	void			*hw_desc;
-	u16			slot_used;
 	u16			idx;
 	struct dma_async_tx_descriptor	async_tx;
 };