[media] tm6000: Add parameter to keep urb bufs allocated

On systems where it cannot be assured that enough continous memory is available
all the time it can be very useful to only allocate the memory once when it is
needed the first time. Afterwards the initially allocated memory will be
reused, so it is ensured that the memory will stay available until the driver
is unloaded.

[mchehab@redhat.com: Codingstyle fixups]
Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/tm6000/tm6000-video.c

@@ -49,12 +49,15 @@
 #define TM6000_MIN_BUF 4
 #define TM6000_DEF_BUF 8
 
+#define TM6000_NUM_URB_BUF 8
+
 #define TM6000_MAX_ISO_PACKETS	46	/* Max number of ISO packets */
 
 /* Declare static vars that will be used as parameters */
 static unsigned int vid_limit = 16;	/* Video memory limit, in Mb */
 static int video_nr = -1;		/* /dev/videoN, -1 for autodetect */
 static int radio_nr = -1;		/* /dev/radioN, -1 for autodetect */
+static int keep_urb;			/* keep urb buffers allocated */
 
 /* Debug level */
 int tm6000_debug;
@@ -537,6 +540,71 @@ static void tm6000_irq_callback(struct urb *urb)
 			urb->status);
 }
 
+/*
+ * Allocate URB buffers
+ */
+static int tm6000_alloc_urb_buffers(struct tm6000_core *dev)
+{
+	int num_bufs = TM6000_NUM_URB_BUF;
+	int i;
+
+	if (dev->urb_buffer != NULL)
+		return 0;
+
+	dev->urb_buffer = kmalloc(sizeof(void *)*num_bufs, GFP_KERNEL);
+	if (!dev->urb_buffer) {
+		tm6000_err("cannot allocate memory for urb buffers\n");
+		return -ENOMEM;
+	}
+
+	dev->urb_dma = kmalloc(sizeof(dma_addr_t *)*num_bufs, GFP_KERNEL);
+	if (!dev->urb_dma) {
+		tm6000_err("cannot allocate memory for urb dma pointers\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < num_bufs; i++) {
+		dev->urb_buffer[i] = usb_alloc_coherent(
+					dev->udev, dev->urb_size,
+					GFP_KERNEL, &dev->urb_dma[i]);
+		if (!dev->urb_buffer[i]) {
+			tm6000_err("unable to allocate %i bytes for transfer buffer %i\n",
+				    dev->urb_size, i);
+			return -ENOMEM;
+		}
+		memset(dev->urb_buffer[i], 0, dev->urb_size);
+	}
+
+	return 0;
+}
+
+/*
+ * Free URB buffers
+ */
+static int tm6000_free_urb_buffers(struct tm6000_core *dev)
+{
+	int i;
+
+	if (dev->urb_buffer == NULL)
+		return 0;
+
+	for (i = 0; i < TM6000_NUM_URB_BUF; i++) {
+		if (dev->urb_buffer[i]) {
+			usb_free_coherent(dev->udev,
+					dev->urb_size,
+					dev->urb_buffer[i],
+					dev->urb_dma[i]);
+			dev->urb_buffer[i] = NULL;
+		}
+	}
+	kfree(dev->urb_buffer);
+	kfree(dev->urb_dma);
+	dev->urb_buffer = NULL;
+	dev->urb_dma = NULL;
+
+	return 0;
+}
+
 /*
  * Stop and Deallocate URBs
  */
@@ -551,18 +619,15 @@ static void tm6000_uninit_isoc(struct tm6000_core *dev)
 		if (urb) {
 			usb_kill_urb(urb);
 			usb_unlink_urb(urb);
-			if (dev->isoc_ctl.transfer_buffer[i]) {
-				usb_free_coherent(dev->udev,
-						urb->transfer_buffer_length,
-						dev->isoc_ctl.transfer_buffer[i],
-						urb->transfer_dma);
-			}
 			usb_free_urb(urb);
 			dev->isoc_ctl.urb[i] = NULL;
 		}
 		dev->isoc_ctl.transfer_buffer[i] = NULL;
 	}
 
+	if (!keep_urb)
+		tm6000_free_urb_buffers(dev);
+
 	kfree(dev->isoc_ctl.urb);
 	kfree(dev->isoc_ctl.transfer_buffer);
 
@@ -572,12 +637,13 @@ static void tm6000_uninit_isoc(struct tm6000_core *dev)
 }
 
 /*
- * Allocate URBs and start IRQ
+ * Assign URBs and start IRQ
  */
 static int tm6000_prepare_isoc(struct tm6000_core *dev)
 {
 	struct tm6000_dmaqueue *dma_q = &dev->vidq;
-	int i, j, sb_size, pipe, size, max_packets, num_bufs = 8;
+	int i, j, sb_size, pipe, size, max_packets;
+	int num_bufs = TM6000_NUM_URB_BUF;
 	struct urb *urb;
 
 	/* De-allocates all pending stuff */
@@ -605,6 +671,7 @@ static int tm6000_prepare_isoc(struct tm6000_core *dev)
 
 	max_packets = TM6000_MAX_ISO_PACKETS;
 	sb_size = max_packets * size;
+	dev->urb_size = sb_size;
 
 	dev->isoc_ctl.num_bufs = num_bufs;
 
@@ -627,6 +694,17 @@ static int tm6000_prepare_isoc(struct tm6000_core *dev)
 		    max_packets, num_bufs, sb_size,
 		    dev->isoc_in.maxsize, size);
 
+
+	if (!dev->urb_buffer && tm6000_alloc_urb_buffers(dev) < 0) {
+		tm6000_err("cannot allocate memory for urb buffers\n");
+
+		/* call free, as some buffers might have been allocated */
+		tm6000_free_urb_buffers(dev);
+		kfree(dev->isoc_ctl.urb);
+		kfree(dev->isoc_ctl.transfer_buffer);
+		return -ENOMEM;
+	}
+
 	/* allocate urbs and transfer buffers */
 	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
 		urb = usb_alloc_urb(max_packets, GFP_KERNEL);
@@ -638,17 +716,8 @@ static int tm6000_prepare_isoc(struct tm6000_core *dev)
 		}
 		dev->isoc_ctl.urb[i] = urb;
 
-		dev->isoc_ctl.transfer_buffer[i] = usb_alloc_coherent(dev->udev,
-			sb_size, GFP_KERNEL, &urb->transfer_dma);
-		if (!dev->isoc_ctl.transfer_buffer[i]) {
-			tm6000_err("unable to allocate %i bytes for transfer"
-					" buffer %i%s\n",
-					sb_size, i,
-					in_interrupt() ? " while in int" : "");
-			tm6000_uninit_isoc(dev);
-			return -ENOMEM;
-		}
-		memset(dev->isoc_ctl.transfer_buffer[i], 0, sb_size);
+		urb->transfer_dma = dev->urb_dma[i];
+		dev->isoc_ctl.transfer_buffer[i] = dev->urb_buffer[i];
 
 		usb_fill_bulk_urb(urb, dev->udev, pipe,
 				  dev->isoc_ctl.transfer_buffer[i], sb_size,
@@ -1826,6 +1895,9 @@ int tm6000_v4l2_unregister(struct tm6000_core *dev)
 {
 	video_unregister_device(dev->vfd);
 
+	/* if URB buffers are still allocated free them now */
+	tm6000_free_urb_buffers(dev);
+
 	if (dev->radio_dev) {
 		if (video_is_registered(dev->radio_dev))
 			video_unregister_device(dev->radio_dev);
@@ -1851,3 +1923,5 @@ MODULE_PARM_DESC(debug, "activates debug info");
 module_param(vid_limit, int, 0644);
 MODULE_PARM_DESC(vid_limit, "capture memory limit in megabytes");
 
+module_param(keep_urb, bool, 0);
+MODULE_PARM_DESC(keep_urb, "Keep urb buffers allocated even when the device is closed by the user");

drivers/media/usb/tm6000/tm6000.h

@@ -264,6 +264,11 @@ struct tm6000_core {
 
 	spinlock_t                   slock;
 
+	/* urb dma buffers */
+	char				**urb_buffer;
+	dma_addr_t			*urb_dma;
+	unsigned int			urb_size;
+
 	unsigned long quirks;
 };