V4L/DVB (13429): cx18: Add Memory Descriptor List (MDL) layer to buffer handling

Add a Memory Descriptor List (MDL) layer to buffer handling to implement
scatter-gather I/O.  Currently there is still only 1 buffer per MDL.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 31 insertions, 14 deletions

diff --git a/drivers/media/video/cx18/cx18-driver.h b/drivers/media/video/cx18/cx18-driver.h
index 1a899e0773d..bed8bcc6541 100644
--- a/drivers/media/video/cx18/cx18-driver.h
+++ b/drivers/media/video/cx18/cx18-driver.h
@@ -246,8 +246,8 @@ struct cx18_options {
 	int radio;		/* enable/disable radio */
 };
 
-/* per-buffer bit flags */
-#define CX18_F_B_NEED_BUF_SWAP  0	/* this buffer should be byte swapped */
+/* per-mdl bit flags */
+#define CX18_F_M_NEED_SWAP  0	/* mdl buffer data must be endianess swapped */
 
 /* per-stream, s_flags */
 #define CX18_F_S_CLAIMED 	3	/* this stream is claimed */
@@ -274,15 +274,26 @@ struct cx18_options {
 struct cx18_buffer {
 	struct list_head list;
 	dma_addr_t dma_handle;
-	u32 id;
-	unsigned long b_flags;
-	unsigned skipped;
 	char *buf;
 
 	u32 bytesused;
 	u32 readpos;
 };
 
+struct cx18_mdl {
+	struct list_head list;
+	u32 id;		/* index into cx->scb->cpu_mdl[] of 1st cx18_mdl_ent */
+
+	unsigned int skipped;
+	unsigned long m_flags;
+
+	struct list_head buf_list;
+	struct cx18_buffer *curr_buf; /* current buffer in list for reading */
+
+	u32 bytesused;
+	u32 readpos;
+};
+
 struct cx18_queue {
 	struct list_head list;
 	atomic_t depth;
@@ -346,14 +357,20 @@ struct cx18_stream {
 				   PCI_DMA_NONE */
 	wait_queue_head_t waitq;
 
-	/* Buffer Stats */
-	u32 buffers;
-	u32 buf_size;
+	/* Buffers */
+	struct list_head buf_pool;	/* buffers not attached to an MDL */
+	u32 buffers;			/* total buffers owned by this stream */
+	u32 buf_size;			/* size in bytes of a single buffer */
+
+	/* MDL sizes - all stream MDLs are the same size */
+	u32 bufs_per_mdl;
+	u32 mdl_size;		/* total bytes in all buffers in a mdl */
 
-	/* Buffer Queues */
-	struct cx18_queue q_free;	/* free buffers */
-	struct cx18_queue q_busy;	/* busy buffers - in use by firmware */
-	struct cx18_queue q_full;	/* full buffers - data for user apps */
+	/* MDL Queues */
+	struct cx18_queue q_free;	/* free - in rotation, not committed */
+	struct cx18_queue q_busy;	/* busy - in use by firmware */
+	struct cx18_queue q_full;	/* full - data for user apps */
+	struct cx18_queue q_idle;	/* idle - not in rotation */
 
 	struct work_struct out_work_order;
 
@@ -481,10 +498,11 @@ struct vbi_info {
 	u32 inserted_frame;
 
 	/*
-	 * A dummy driver stream transfer buffer with a copy of the next
+	 * A dummy driver stream transfer mdl & buffer with a copy of the next
 	 * sliced_mpeg_data[] buffer for output to userland apps.
 	 * Only used in cx18-fileops.c, but its state needs to persist at times.
 	 */
+	struct cx18_mdl sliced_mpeg_mdl;
 	struct cx18_buffer sliced_mpeg_buf;
 };
 
@@ -511,7 +529,6 @@ struct cx18 {
 	u8 is_60hz;
 	u8 nof_inputs;		/* number of video inputs */
 	u8 nof_audio_inputs;	/* number of audio inputs */
-	u16 buffer_id;		/* buffer ID counter */
 	u32 v4l2_cap;		/* V4L2 capabilities of card */
 	u32 hw_flags; 		/* Hardware description of the board */
 	unsigned int free_mdl_idx;