media: uvcvideo: Refactor URB descriptors

We currently store three separate arrays for each URB reference we hold.

Objectify the data needed to track URBs into a single uvc_urb structure,
allowing better object management and tracking of the URB.

All accesses to the data pointers through stream, are converted to use a
uvc_urb pointer for consistency.
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/uvc/uvc_video.c

@@ -1506,14 +1506,16 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream)
 	unsigned int i;
 
 	for (i = 0; i < UVC_URBS; ++i) {
-		if (stream->urb_buffer[i]) {
+		struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
+
+		if (uvc_urb->buffer) {
 #ifndef CONFIG_DMA_NONCOHERENT
 			usb_free_coherent(stream->dev->udev, stream->urb_size,
-				stream->urb_buffer[i], stream->urb_dma[i]);
+					uvc_urb->buffer, uvc_urb->dma);
 #else
-			kfree(stream->urb_buffer[i]);
+			kfree(uvc_urb->buffer);
 #endif
-			stream->urb_buffer[i] = NULL;
+			uvc_urb->buffer = NULL;
 		}
 	}
 
@@ -1551,16 +1553,18 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
 	/* Retry allocations until one succeed. */
 	for (; npackets > 1; npackets /= 2) {
 		for (i = 0; i < UVC_URBS; ++i) {
+			struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
+
 			stream->urb_size = psize * npackets;
 #ifndef CONFIG_DMA_NONCOHERENT
-			stream->urb_buffer[i] = usb_alloc_coherent(
+			uvc_urb->buffer = usb_alloc_coherent(
 				stream->dev->udev, stream->urb_size,
-				gfp_flags | __GFP_NOWARN, &stream->urb_dma[i]);
+				gfp_flags | __GFP_NOWARN, &uvc_urb->dma);
 #else
-			stream->urb_buffer[i] =
+			uvc_urb->buffer =
 			    kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN);
 #endif
-			if (!stream->urb_buffer[i]) {
+			if (!uvc_urb->buffer) {
 				uvc_free_urb_buffers(stream);
 				break;
 			}
@@ -1590,13 +1594,15 @@ static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers)
 	uvc_video_stats_stop(stream);
 
 	for (i = 0; i < UVC_URBS; ++i) {
-		urb = stream->urb[i];
+		struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
+
+		urb = uvc_urb->urb;
 		if (urb == NULL)
 			continue;
 
 		usb_kill_urb(urb);
 		usb_free_urb(urb);
-		stream->urb[i] = NULL;
+		uvc_urb->urb = NULL;
 	}
 
 	if (free_buffers)
@@ -1651,6 +1657,8 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
 	size = npackets * psize;
 
 	for (i = 0; i < UVC_URBS; ++i) {
+		struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
+
 		urb = usb_alloc_urb(npackets, gfp_flags);
 		if (urb == NULL) {
 			uvc_uninit_video(stream, 1);
@@ -1663,12 +1671,12 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
 				ep->desc.bEndpointAddress);
 #ifndef CONFIG_DMA_NONCOHERENT
 		urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
-		urb->transfer_dma = stream->urb_dma[i];
+		urb->transfer_dma = uvc_urb->dma;
 #else
 		urb->transfer_flags = URB_ISO_ASAP;
 #endif
 		urb->interval = ep->desc.bInterval;
-		urb->transfer_buffer = stream->urb_buffer[i];
+		urb->transfer_buffer = uvc_urb->buffer;
 		urb->complete = uvc_video_complete;
 		urb->number_of_packets = npackets;
 		urb->transfer_buffer_length = size;
@@ -1678,7 +1686,7 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
 			urb->iso_frame_desc[j].length = psize;
 		}
 
-		stream->urb[i] = urb;
+		uvc_urb->urb = urb;
 	}
 
 	return 0;
@@ -1717,21 +1725,22 @@ static int uvc_init_video_bulk(struct uvc_streaming *stream,
 		size = 0;
 
 	for (i = 0; i < UVC_URBS; ++i) {
+		struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
+
 		urb = usb_alloc_urb(0, gfp_flags);
 		if (urb == NULL) {
 			uvc_uninit_video(stream, 1);
 			return -ENOMEM;
 		}
 
-		usb_fill_bulk_urb(urb, stream->dev->udev, pipe,
-			stream->urb_buffer[i], size, uvc_video_complete,
-			stream);
+		usb_fill_bulk_urb(urb, stream->dev->udev, pipe, uvc_urb->buffer,
+				  size, uvc_video_complete, stream);
 #ifndef CONFIG_DMA_NONCOHERENT
 		urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
-		urb->transfer_dma = stream->urb_dma[i];
+		urb->transfer_dma = uvc_urb->dma;
 #endif
 
-		stream->urb[i] = urb;
+		uvc_urb->urb = urb;
 	}
 
 	return 0;
@@ -1822,7 +1831,9 @@ static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags)
 
 	/* Submit the URBs. */
 	for (i = 0; i < UVC_URBS; ++i) {
-		ret = usb_submit_urb(stream->urb[i], gfp_flags);
+		struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
+
+		ret = usb_submit_urb(uvc_urb->urb, gfp_flags);
 		if (ret < 0) {
 			uvc_printk(KERN_ERR, "Failed to submit URB %u "
 					"(%d).\n", i, ret);

drivers/media/usb/uvc/uvcvideo.h

@@ -490,6 +490,20 @@ struct uvc_stats_stream {
 
 #define UVC_METATADA_BUF_SIZE 1024
 
+/**
+ * struct uvc_urb - URB context management structure
+ *
+ * @urb: the URB described by this context structure
+ * @buffer: memory storage for the URB
+ * @dma: DMA coherent addressing for the urb_buffer
+ */
+struct uvc_urb {
+	struct urb *urb;
+
+	char *buffer;
+	dma_addr_t dma;
+};
+
 struct uvc_streaming {
 	struct list_head list;
 	struct uvc_device *dev;
@@ -538,9 +552,7 @@ struct uvc_streaming {
 		u32 max_payload_size;
 	} bulk;
 
-	struct urb *urb[UVC_URBS];
-	char *urb_buffer[UVC_URBS];
-	dma_addr_t urb_dma[UVC_URBS];
+	struct uvc_urb uvc_urb[UVC_URBS];
 	unsigned int urb_size;
 
 	u32 sequence;