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 1a899e0773d7..bed8bcc65411 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;