V4L/DVB (9891): cx18 Replace magic number 63 with CX18_MAX_FW_MDLS_PER_STREAM

Removed magic number that referred to firmware limit on the number of
MDLs the firmware can maintain for any stream at any one time.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-driver.h

@@ -116,7 +116,7 @@
 #define CX18_DEFAULT_ENC_PCM_BUFFERS 1
 
 /* Maximum firmware DMA buffers per stream */
-#define CX18_MAX_MDLS_PER_STREAM 63
+#define CX18_MAX_FW_MDLS_PER_STREAM 63
 
 /* DMA buffer, default size in kB allocated */
 #define CX18_DEFAULT_ENC_TS_BUFSIZE   32
@@ -255,7 +255,8 @@ struct cx18_scb; /* forward reference */
 
 
 #define CX18_MAX_MDL_ACKS 2
-#define CX18_MAX_EPU_WORK_ORDERS 70 /* CPU_DE_RELEASE_MDL bursts 63 commands */
+#define CX18_MAX_EPU_WORK_ORDERS (CX18_MAX_FW_MDLS_PER_STREAM + 7)
+/* CPU_DE_RELEASE_MDL can burst CX18_MAX_FW_MDLS_PER_STREAM orders in a group */
 
 #define CX18_F_EWO_MB_STALE_UPON_RECEIPT 0x1
 #define CX18_F_EWO_MB_STALE_WHILE_PROC   0x2

drivers/media/video/cx18/cx18-queue.c

@@ -55,8 +55,9 @@ struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
 
 	mutex_lock(&s->qlock);
 
-	/* q_busy is restricted to 63 buffers to stay within firmware limits */
-	if (q == &s->q_busy && atomic_read(&q->buffers) >= 63)
+	/* q_busy is restricted to a max buffer count imposed by firmware */
+	if (q == &s->q_busy &&
+	    atomic_read(&q->buffers) >= CX18_MAX_FW_MDLS_PER_STREAM)
 		q = &s->q_free;
 
 	if (to_front)

drivers/media/video/cx18/cx18-streams.c

@@ -425,7 +425,7 @@ void cx18_stream_load_fw_queue(struct cx18_stream *s)
 	struct cx18_buffer *buf;
 
 	if (atomic_read(&s->q_free.buffers) == 0 ||
-	    atomic_read(&s->q_busy.buffers) >= 63)
+	    atomic_read(&s->q_busy.buffers) >= CX18_MAX_FW_MDLS_PER_STREAM)
 		return;
 
 	/* Move from q_free to q_busy notifying the firmware, until the limit */
@@ -434,7 +434,8 @@ void cx18_stream_load_fw_queue(struct cx18_stream *s)
 		if (buf == NULL)
 			break;
 		q = cx18_stream_put_buf_fw(s, buf);
-	} while (atomic_read(&s->q_busy.buffers) < 63 && q == &s->q_busy);
+	} while (atomic_read(&s->q_busy.buffers) < CX18_MAX_FW_MDLS_PER_STREAM
+		 && q == &s->q_busy);
 }
 
 int cx18_start_v4l2_encode_stream(struct cx18_stream *s)