media:uvc: supports dynamic setting of urb configuration

Frames are corrupted for higher resolution with default URB queue
size and frame size. This patch creates a sysfs node to support
dynamic setting of number of packers per urb  and maximum packet
size for higher resolution frames.
$ find . -name urb_config.
$ echo qsize:fsize > urb_config.

Change-Id: I70aaad824049acdc21a8a52242066a6437b96833
Signed-off-by: Arjun Singh <quic_arsingh@quicinc.com>

drivers/media/usb/uvc/uvc_driver.c

@@ -2093,6 +2093,71 @@ struct uvc_device_info {
 	u32	meta_format;
 };
 
+/* ------------------------------------------------------------------------
+ * set urb queue size and urb packet size
+ *
+ */
+static ssize_t store_urb_config(struct device *dev,
+		struct device_attribute *attr, const char *buff, size_t count)
+{
+	struct uvc_streaming *stream;
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct uvc_device *udev = usb_get_intfdata(intf);
+	long max_urb, max_urb_packets;
+	int ret;
+	char *arr, *tmp;
+
+	arr = kstrdup(buff, GFP_KERNEL);
+
+	if (!arr)
+		return -ENOMEM;
+
+	tmp = strsep(&arr, ":");
+
+	if (!tmp)
+		return -EINVAL;
+
+	ret = kstrtol(tmp, 10, &max_urb);
+		if (ret < 0)
+			return ret;
+
+	tmp = strsep(&arr, ":");
+	if (!tmp)
+		return -EINVAL;
+
+	ret = kstrtol(tmp, 10, &max_urb_packets);
+		if (ret < 0)
+			return ret;
+
+	if (max_urb <= 0 || max_urb > 128 ||
+		max_urb_packets <= 0 || max_urb_packets > 128)
+		return -EINVAL;
+
+	list_for_each_entry(stream, &udev->streams, list) {
+		if (stream->refcnt)
+			continue;
+		stream->max_urb = max_urb;
+		stream->max_urb_packets = max_urb_packets;
+	}
+
+	return count;
+}
+
+static ssize_t show_urb_config(struct device *dev,
+		struct device_attribute *attr, char *buff)
+{
+	return 0;
+}
+
+static struct device_attribute urb_config_attr = {
+	.attr = {
+		.name = "urb_config",
+		.mode = 00660,
+	},
+	.show = show_urb_config,
+	.store = store_urb_config,
+};
+
 static int uvc_probe(struct usb_interface *intf,
 		     const struct usb_device_id *id)
 {
@@ -2225,6 +2290,12 @@ static int uvc_probe(struct usb_interface *intf,
 
 	uvc_trace(UVC_TRACE_PROBE, "UVC device initialized.\n");
 	usb_enable_autosuspend(udev);
+
+	/* sysfs file for dynamically setting urb configs */
+	ret = sysfs_create_file(&dev->intf->dev.kobj, &urb_config_attr.attr);
+	if (ret != 0)
+		pr_info("Unable to initialize urb configuration: %d\n", ret);
+
 	return 0;
 
 error:

drivers/media/usb/uvc/uvc_video.c

@@ -1515,7 +1515,7 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream)
 {
 	unsigned int i;
 
-	for (i = 0; i < UVC_URBS; ++i) {
+	for (i = 0; i < stream->max_urb; ++i) {
 		if (stream->urb_buffer[i]) {
 #ifndef CONFIG_DMA_NONCOHERENT
 			usb_free_coherent(stream->dev->udev, stream->urb_size,
@@ -1555,12 +1555,22 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
 	 * payloads across multiple URBs.
 	 */
 	npackets = DIV_ROUND_UP(size, psize);
-	if (npackets > UVC_MAX_PACKETS)
-		npackets = UVC_MAX_PACKETS;
+	if (npackets > stream->max_urb_packets)
+		npackets = stream->max_urb_packets;
+
+
+	/* Allocate memory for storing URB pointers */
+	stream->urb = kcalloc(stream->max_urb,
+			sizeof(struct urb *), gfp_flags | __GFP_NOWARN);
+	stream->urb_buffer = kcalloc(stream->max_urb,
+			sizeof(char *), gfp_flags | __GFP_NOWARN);
+	stream->urb_dma = kcalloc(stream->max_urb,
+			sizeof(dma_addr_t), gfp_flags | __GFP_NOWARN);
+
 
 	/* Retry allocations until one succeed. */
 	for (; npackets > 1; npackets /= 2) {
-		for (i = 0; i < UVC_URBS; ++i) {
+		for (i = 0; i < stream->max_urb; ++i) {
 			stream->urb_size = psize * npackets;
 #ifndef CONFIG_DMA_NONCOHERENT
 			stream->urb_buffer[i] = usb_alloc_coherent(
@@ -1576,10 +1586,10 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
 			}
 		}
 
-		if (i == UVC_URBS) {
-			uvc_trace(UVC_TRACE_VIDEO, "Allocated %u URB buffers "
-				"of %ux%u bytes each.\n", UVC_URBS, npackets,
-				psize);
+		if (i == stream->max_urb) {
+			uvc_trace(UVC_TRACE_VIDEO,
+				"Allocated %u URB buffers of %ux%u bytes each.\n",
+				stream->max_urb, npackets, psize);
 			return npackets;
 		}
 	}
@@ -1599,7 +1609,7 @@ static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers)
 
 	uvc_video_stats_stop(stream);
 
-	for (i = 0; i < UVC_URBS; ++i) {
+	for (i = 0; i < stream->max_urb; ++i) {
 		urb = stream->urb[i];
 		if (urb == NULL)
 			continue;
@@ -1611,6 +1621,8 @@ static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers)
 
 	if (free_buffers)
 		uvc_free_urb_buffers(stream);
+
+	stream->refcnt--;
 }
 
 /*
@@ -1660,7 +1672,7 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
 
 	size = npackets * psize;
 
-	for (i = 0; i < UVC_URBS; ++i) {
+	for (i = 0; i < stream->max_urb; ++i) {
 		urb = usb_alloc_urb(npackets, gfp_flags);
 		if (urb == NULL) {
 			uvc_uninit_video(stream, 1);
@@ -1726,7 +1738,7 @@ static int uvc_init_video_bulk(struct uvc_streaming *stream,
 	if (stream->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
 		size = 0;
 
-	for (i = 0; i < UVC_URBS; ++i) {
+	for (i = 0; i < stream->max_urb; ++i) {
 		urb = usb_alloc_urb(0, gfp_flags);
 		if (urb == NULL) {
 			uvc_uninit_video(stream, 1);
@@ -1831,7 +1843,8 @@ static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags)
 		return ret;
 
 	/* Submit the URBs. */
-	for (i = 0; i < UVC_URBS; ++i) {
+	stream->refcnt++;
+	for (i = 0; i < stream->max_urb; ++i) {
 		ret = usb_submit_urb(stream->urb[i], gfp_flags);
 		if (ret < 0) {
 			uvc_printk(KERN_ERR, "Failed to submit URB %u "
@@ -1992,6 +2005,9 @@ int uvc_video_init(struct uvc_streaming *stream)
 	stream->cur_format = format;
 	stream->cur_frame = frame;
 
+	stream->max_urb = UVC_URBS;
+	stream->max_urb_packets = UVC_MAX_PACKETS;
+
 	/* Select the video decoding function */
 	if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
 		if (stream->dev->quirks & UVC_QUIRK_BUILTIN_ISIGHT)

drivers/media/usb/uvc/uvcvideo.h

@@ -535,9 +535,9 @@ 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 urb **urb;
+	char **urb_buffer;
+	dma_addr_t *urb_dma;
 	unsigned int urb_size;
 
 	u32 sequence;
@@ -570,6 +570,15 @@ struct uvc_streaming {
 
 		spinlock_t lock;
 	} clock;
+
+	/* Maximum number of URBs that can be submitted */
+	u32 max_urb;
+
+	/* Maximum number of packets per URB */
+	u32 max_urb_packets;
+
+	/*set if stream in progress */
+	u8 refcnt;
 };
 
 struct uvc_device {