[media] em28xx: pre-allocate DVB isoc transfer buffers

On MIPS/ARM set-top-boxes, as well as old x86 PCs, memory allocation failures
in the em28xx driver are common, due to memory fragmentation over time, that
makes impossible to allocate large chunks of coherent memory.
A typical system with 256/512 MB of RAM fails after just 1 day of uptime (see
the old thread for detailed reports and crashlogs).

In fact, the em28xx driver allocates memory for USB isoc transfers at runtime,
as opposite to the dvb-usb drivers that allocates the USB buffers when the
device is initialized, and frees them when the device is disconnected.

Moreover, in digital mode the USB isoc transfer buffers are freed, allocated
and cleared every time the user selects a new channel, wasting time and
resources.

This patch solves both problems by allocating DVB isoc transfer buffers in
em28xx_usb_probe(), and freeing them in em28xx_usb_disconnect().
In fact, the buffers size and number depend only on the max USB packet size
that is parsed from the USB descriptors in em28xx_usb_probe(), so it can
never change for a given device.

This approach makes no sense in analog mode (as the buffer size depends on
the alternate mode selected at runtime), the patch creates two separate sets
of buffers for digital and analog modes.

For digital-only devices, USB buffers are created when the device is probed
and freed when the device is disconnected.
For analog-only devices, nothing changes: isoc buffers are created at runtime.
For hybrid devices, two sets of buffers are maintained: the digital-mode
buffers are created when the device is probed, and freed when the device is
disconnected; analog-mode buffers are created/destroyed at runtime as before.
So, in analog mode, digital and analog buffers coexists at the same time: this
can be justified by the fact that digital mode is by far more commonly used
nowadays, so it makes sense to optimize the driver for this use case scenario.

The patch has been tested in the last few days on a x86 PC and a MIPS
set-top-box, with the PCTV 290e (digital only) and the Terratec Hybrid XS
(hybrid device). With the latter, I switched several times between analog and
digital mode (Kaffeine/TvTime) with no issue at all.
I unplugged/plugged the devices several times with no problem.
Also, after over 3 days of normal usage in the MPIS set-top-box, the PCTV 290e
was still up and running.
Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-cards.c

@@ -3307,6 +3307,17 @@ static int em28xx_usb_probe(struct usb_interface *interface,
 		goto unlock_and_free;
 	}
 
+	if (has_dvb) {
+		/* pre-allocate DVB isoc transfer buffers */
+		retval = em28xx_alloc_isoc(dev, EM28XX_DIGITAL_MODE,
+					   EM28XX_DVB_MAX_PACKETS,
+					   EM28XX_DVB_NUM_BUFS,
+					   dev->dvb_max_pkt_size);
+		if (retval) {
+			goto unlock_and_free;
+		}
+	}
+
 	request_modules(dev);
 
 	/* Should be the last thing to do, to avoid newer udev's to
@@ -3379,7 +3390,7 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
 		     video_device_node_name(dev->vdev));
 
 		dev->state |= DEV_MISCONFIGURED;
-		em28xx_uninit_isoc(dev);
+		em28xx_uninit_isoc(dev, dev->mode);
 		dev->state |= DEV_DISCONNECTED;
 		wake_up_interruptible(&dev->wait_frame);
 		wake_up_interruptible(&dev->wait_stream);
@@ -3388,6 +3399,9 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
 		em28xx_release_resources(dev);
 	}
 
+	/* free DVB isoc buffers */
+	em28xx_uninit_isoc(dev, EM28XX_DIGITAL_MODE);
+
 	mutex_unlock(&dev->lock);
 
 	em28xx_close_extension(dev);

drivers/media/video/em28xx/em28xx-core.c

@@ -666,6 +666,7 @@ int em28xx_capture_start(struct em28xx *dev, int start)
 
 	return rc;
 }
+EXPORT_SYMBOL_GPL(em28xx_capture_start);
 
 int em28xx_vbi_supported(struct em28xx *dev)
 {
@@ -961,146 +962,192 @@ static void em28xx_irq_callback(struct urb *urb)
 /*
  * Stop and Deallocate URBs
  */
-void em28xx_uninit_isoc(struct em28xx *dev)
+void em28xx_uninit_isoc(struct em28xx *dev, enum em28xx_mode mode)
 {
 	struct urb *urb;
+	struct em28xx_usb_isoc_bufs *isoc_bufs;
 	int i;
 
-	em28xx_isocdbg("em28xx: called em28xx_uninit_isoc\n");
+	em28xx_isocdbg("em28xx: called em28xx_uninit_isoc in mode %d\n", mode);
+
+	if (mode == EM28XX_DIGITAL_MODE)
+		isoc_bufs = &dev->isoc_ctl.digital_bufs;
+	else
+		isoc_bufs = &dev->isoc_ctl.analog_bufs;
 
 	dev->isoc_ctl.nfields = -1;
-	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
-		urb = dev->isoc_ctl.urb[i];
+	for (i = 0; i < isoc_bufs->num_bufs; i++) {
+		urb = isoc_bufs->urb[i];
 		if (urb) {
 			if (!irqs_disabled())
 				usb_kill_urb(urb);
 			else
 				usb_unlink_urb(urb);
 
-			if (dev->isoc_ctl.transfer_buffer[i]) {
+			if (isoc_bufs->transfer_buffer[i]) {
 				usb_free_coherent(dev->udev,
 					urb->transfer_buffer_length,
-					dev->isoc_ctl.transfer_buffer[i],
+					isoc_bufs->transfer_buffer[i],
 					urb->transfer_dma);
 			}
 			usb_free_urb(urb);
-			dev->isoc_ctl.urb[i] = NULL;
+			isoc_bufs->urb[i] = NULL;
 		}
-		dev->isoc_ctl.transfer_buffer[i] = NULL;
+		isoc_bufs->transfer_buffer[i] = NULL;
 	}
 
-	kfree(dev->isoc_ctl.urb);
-	kfree(dev->isoc_ctl.transfer_buffer);
+	kfree(isoc_bufs->urb);
+	kfree(isoc_bufs->transfer_buffer);
 
-	dev->isoc_ctl.urb = NULL;
-	dev->isoc_ctl.transfer_buffer = NULL;
-	dev->isoc_ctl.num_bufs = 0;
+	isoc_bufs->urb = NULL;
+	isoc_bufs->transfer_buffer = NULL;
+	isoc_bufs->num_bufs = 0;
 
 	em28xx_capture_start(dev, 0);
 }
 EXPORT_SYMBOL_GPL(em28xx_uninit_isoc);
 
 /*
- * Allocate URBs and start IRQ
+ * Allocate URBs
  */
-int em28xx_init_isoc(struct em28xx *dev, int max_packets,
-		     int num_bufs, int max_pkt_size,
-		     int (*isoc_copy) (struct em28xx *dev, struct urb *urb))
+int em28xx_alloc_isoc(struct em28xx *dev, enum em28xx_mode mode,
+		      int max_packets, int num_bufs, int max_pkt_size)
 {
-	struct em28xx_dmaqueue *dma_q = &dev->vidq;
-	struct em28xx_dmaqueue *vbi_dma_q = &dev->vbiq;
+	struct em28xx_usb_isoc_bufs *isoc_bufs;
 	int i;
 	int sb_size, pipe;
 	struct urb *urb;
 	int j, k;
-	int rc;
 
-	em28xx_isocdbg("em28xx: called em28xx_prepare_isoc\n");
+	em28xx_isocdbg("em28xx: called em28xx_alloc_isoc in mode %d\n", mode);
+
+	if (mode == EM28XX_DIGITAL_MODE)
+		isoc_bufs = &dev->isoc_ctl.digital_bufs;
+	else
+		isoc_bufs = &dev->isoc_ctl.analog_bufs;
 
 	/* De-allocates all pending stuff */
-	em28xx_uninit_isoc(dev);
+	em28xx_uninit_isoc(dev, mode);
 
-	dev->isoc_ctl.isoc_copy = isoc_copy;
-	dev->isoc_ctl.num_bufs = num_bufs;
+	isoc_bufs->num_bufs = num_bufs;
 
-	dev->isoc_ctl.urb = kzalloc(sizeof(void *)*num_bufs,  GFP_KERNEL);
-	if (!dev->isoc_ctl.urb) {
+	isoc_bufs->urb = kzalloc(sizeof(void *)*num_bufs,  GFP_KERNEL);
+	if (!isoc_bufs->urb) {
 		em28xx_errdev("cannot alloc memory for usb buffers\n");
 		return -ENOMEM;
 	}
 
-	dev->isoc_ctl.transfer_buffer = kzalloc(sizeof(void *)*num_bufs,
-					      GFP_KERNEL);
-	if (!dev->isoc_ctl.transfer_buffer) {
+	isoc_bufs->transfer_buffer = kzalloc(sizeof(void *)*num_bufs,
+					     GFP_KERNEL);
+	if (!isoc_bufs->transfer_buffer) {
 		em28xx_errdev("cannot allocate memory for usb transfer\n");
-		kfree(dev->isoc_ctl.urb);
+		kfree(isoc_bufs->urb);
 		return -ENOMEM;
 	}
 
-	dev->isoc_ctl.max_pkt_size = max_pkt_size;
+	isoc_bufs->max_pkt_size = max_pkt_size;
+	isoc_bufs->num_packets = max_packets;
 	dev->isoc_ctl.vid_buf = NULL;
 	dev->isoc_ctl.vbi_buf = NULL;
 
-	sb_size = max_packets * dev->isoc_ctl.max_pkt_size;
+	sb_size = isoc_bufs->num_packets * isoc_bufs->max_pkt_size;
 
 	/* allocate urbs and transfer buffers */
-	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
-		urb = usb_alloc_urb(max_packets, GFP_KERNEL);
+	for (i = 0; i < isoc_bufs->num_bufs; i++) {
+		urb = usb_alloc_urb(isoc_bufs->num_packets, GFP_KERNEL);
 		if (!urb) {
 			em28xx_err("cannot alloc isoc_ctl.urb %i\n", i);
-			em28xx_uninit_isoc(dev);
+			em28xx_uninit_isoc(dev, mode);
 			return -ENOMEM;
 		}
-		dev->isoc_ctl.urb[i] = urb;
+		isoc_bufs->urb[i] = urb;
 
-		dev->isoc_ctl.transfer_buffer[i] = usb_alloc_coherent(dev->udev,
+		isoc_bufs->transfer_buffer[i] = usb_alloc_coherent(dev->udev,
 			sb_size, GFP_KERNEL, &urb->transfer_dma);
-		if (!dev->isoc_ctl.transfer_buffer[i]) {
+		if (!isoc_bufs->transfer_buffer[i]) {
 			em28xx_err("unable to allocate %i bytes for transfer"
 					" buffer %i%s\n",
 					sb_size, i,
 					in_interrupt() ? " while in int" : "");
-			em28xx_uninit_isoc(dev);
+			em28xx_uninit_isoc(dev, mode);
 			return -ENOMEM;
 		}
-		memset(dev->isoc_ctl.transfer_buffer[i], 0, sb_size);
+		memset(isoc_bufs->transfer_buffer[i], 0, sb_size);
 
 		/* FIXME: this is a hack - should be
 			'desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK'
 			should also be using 'desc.bInterval'
 		 */
 		pipe = usb_rcvisocpipe(dev->udev,
-				       dev->mode == EM28XX_ANALOG_MODE ?
+				       mode == EM28XX_ANALOG_MODE ?
 				       EM28XX_EP_ANALOG : EM28XX_EP_DIGITAL);
 
 		usb_fill_int_urb(urb, dev->udev, pipe,
-				 dev->isoc_ctl.transfer_buffer[i], sb_size,
+				 isoc_bufs->transfer_buffer[i], sb_size,
 				 em28xx_irq_callback, dev, 1);
 
-		urb->number_of_packets = max_packets;
+		urb->number_of_packets = isoc_bufs->num_packets;
 		urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
 
 		k = 0;
-		for (j = 0; j < max_packets; j++) {
+		for (j = 0; j < isoc_bufs->num_packets; j++) {
 			urb->iso_frame_desc[j].offset = k;
 			urb->iso_frame_desc[j].length =
-						dev->isoc_ctl.max_pkt_size;
-			k += dev->isoc_ctl.max_pkt_size;
+						isoc_bufs->max_pkt_size;
+			k += isoc_bufs->max_pkt_size;
 		}
 	}
 
+	return 0;
+}
+EXPORT_SYMBOL_GPL(em28xx_alloc_isoc);
+
+/*
+ * Allocate URBs and start IRQ
+ */
+int em28xx_init_isoc(struct em28xx *dev, enum em28xx_mode mode,
+		     int max_packets, int num_bufs, int max_pkt_size,
+		     int (*isoc_copy) (struct em28xx *dev, struct urb *urb))
+{
+	struct em28xx_dmaqueue *dma_q = &dev->vidq;
+	struct em28xx_dmaqueue *vbi_dma_q = &dev->vbiq;
+	struct em28xx_usb_isoc_bufs *isoc_bufs;
+	int i;
+	int rc;
+	int alloc;
+
+	em28xx_isocdbg("em28xx: called em28xx_init_isoc in mode %d\n", mode);
+
+	dev->isoc_ctl.isoc_copy = isoc_copy;
+
+	if (mode == EM28XX_DIGITAL_MODE) {
+		isoc_bufs = &dev->isoc_ctl.digital_bufs;
+		/* no need to free/alloc isoc buffers in digital mode */
+		alloc = 0;
+	} else {
+		isoc_bufs = &dev->isoc_ctl.analog_bufs;
+		alloc = 1;
+	}
+
+	if (alloc) {
+		rc = em28xx_alloc_isoc(dev, mode, max_packets,
+				       num_bufs, max_pkt_size);
+		if (rc)
+			return rc;
+	}
+
 	init_waitqueue_head(&dma_q->wq);
 	init_waitqueue_head(&vbi_dma_q->wq);
 
 	em28xx_capture_start(dev, 1);
 
 	/* submit urbs and enables IRQ */
-	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
-		rc = usb_submit_urb(dev->isoc_ctl.urb[i], GFP_ATOMIC);
+	for (i = 0; i < isoc_bufs->num_bufs; i++) {
+		rc = usb_submit_urb(isoc_bufs->urb[i], GFP_ATOMIC);
 		if (rc) {
 			em28xx_err("submit of urb %i failed (error=%i)\n", i,
 				   rc);
-			em28xx_uninit_isoc(dev);
+			em28xx_uninit_isoc(dev, mode);
 			return rc;
 		}
 	}

drivers/media/video/em28xx/em28xx-dvb.c

@@ -61,9 +61,6 @@ if (debug >= level) 						\
 	printk(KERN_DEBUG "%s/2-dvb: " fmt, dev->name, ## arg);	\
 } while (0)
 
-#define EM28XX_DVB_NUM_BUFS 5
-#define EM28XX_DVB_MAX_PACKETS 64
-
 struct em28xx_dvb {
 	struct dvb_frontend        *fe[2];
 
@@ -172,20 +169,21 @@ static int em28xx_start_streaming(struct em28xx_dvb *dvb)
 	max_dvb_packet_size = dev->dvb_max_pkt_size;
 	if (max_dvb_packet_size < 0)
 		return max_dvb_packet_size;
-	dprintk(1, "Using %d buffers each with %d bytes\n",
+	dprintk(1, "Using %d buffers each with %d x %d bytes\n",
 		EM28XX_DVB_NUM_BUFS,
+		EM28XX_DVB_MAX_PACKETS,
 		max_dvb_packet_size);
 
-	return em28xx_init_isoc(dev, EM28XX_DVB_MAX_PACKETS,
-				EM28XX_DVB_NUM_BUFS, max_dvb_packet_size,
-				em28xx_dvb_isoc_copy);
+	return em28xx_init_isoc(dev, EM28XX_DIGITAL_MODE,
+				EM28XX_DVB_MAX_PACKETS, EM28XX_DVB_NUM_BUFS,
+				max_dvb_packet_size, em28xx_dvb_isoc_copy);
 }
 
 static int em28xx_stop_streaming(struct em28xx_dvb *dvb)
 {
 	struct em28xx *dev = dvb->adapter.priv;
 
-	em28xx_uninit_isoc(dev);
+	em28xx_capture_start(dev, 0);
 
 	em28xx_set_mode(dev, EM28XX_SUSPEND);
 

drivers/media/video/em28xx/em28xx-video.c

@@ -760,17 +760,19 @@ buffer_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb,
 			goto fail;
 	}
 
-	if (!dev->isoc_ctl.num_bufs)
+	if (!dev->isoc_ctl.analog_bufs.num_bufs)
 		urb_init = 1;
 
 	if (urb_init) {
 		if (em28xx_vbi_supported(dev) == 1)
-			rc = em28xx_init_isoc(dev, EM28XX_NUM_PACKETS,
+			rc = em28xx_init_isoc(dev, EM28XX_ANALOG_MODE,
+					      EM28XX_NUM_PACKETS,
 					      EM28XX_NUM_BUFS,
 					      dev->max_pkt_size,
 					      em28xx_isoc_copy_vbi);
 		else
-			rc = em28xx_init_isoc(dev, EM28XX_NUM_PACKETS,
+			rc = em28xx_init_isoc(dev, EM28XX_ANALOG_MODE,
+					      EM28XX_NUM_PACKETS,
 					      EM28XX_NUM_BUFS,
 					      dev->max_pkt_size,
 					      em28xx_isoc_copy);
@@ -2267,7 +2269,7 @@ static int em28xx_v4l2_close(struct file *filp)
 		v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 0);
 
 		/* do this before setting alternate! */
-		em28xx_uninit_isoc(dev);
+		em28xx_uninit_isoc(dev, EM28XX_ANALOG_MODE);
 		em28xx_set_mode(dev, EM28XX_SUSPEND);
 
 		/* set alternate 0 */

drivers/media/video/em28xx/em28xx.h

@@ -151,12 +151,14 @@
 
 /* number of buffers for isoc transfers */
 #define EM28XX_NUM_BUFS 5
+#define EM28XX_DVB_NUM_BUFS 5
 
 /* number of packets for each buffer
    windows requests only 64 packets .. so we better do the same
    this is what I found out for all alternate numbers there!
  */
 #define EM28XX_NUM_PACKETS 64
+#define EM28XX_DVB_MAX_PACKETS 64
 
 #define EM28XX_INTERLACED_DEFAULT 1
 
@@ -197,10 +199,13 @@ enum em28xx_mode {
 
 struct em28xx;
 
-struct em28xx_usb_isoc_ctl {
+struct em28xx_usb_isoc_bufs {
 		/* max packet size of isoc transaction */
 	int				max_pkt_size;
 
+		/* number of packets in each buffer */
+	int				num_packets;
+
 		/* number of allocated urbs */
 	int				num_bufs;
 
@@ -209,6 +214,14 @@ struct em28xx_usb_isoc_ctl {
 
 		/* transfer buffers for isoc transfer */
 	char				**transfer_buffer;
+};
+
+struct em28xx_usb_isoc_ctl {
+		/* isoc transfer buffers for analog mode */
+	struct em28xx_usb_isoc_bufs	analog_bufs;
+
+		/* isoc transfer buffers for digital mode */
+	struct em28xx_usb_isoc_bufs	digital_bufs;
 
 		/* Last buffer command and region */
 	u8				cmd;
@@ -676,10 +689,12 @@ int em28xx_vbi_supported(struct em28xx *dev);
 int em28xx_set_outfmt(struct em28xx *dev);
 int em28xx_resolution_set(struct em28xx *dev);
 int em28xx_set_alternate(struct em28xx *dev);
-int em28xx_init_isoc(struct em28xx *dev, int max_packets,
-		     int num_bufs, int max_pkt_size,
+int em28xx_alloc_isoc(struct em28xx *dev, enum em28xx_mode mode,
+		      int max_packets, int num_bufs, int max_pkt_size);
+int em28xx_init_isoc(struct em28xx *dev, enum em28xx_mode mode,
+		     int max_packets, int num_bufs, int max_pkt_size,
 		     int (*isoc_copy) (struct em28xx *dev, struct urb *urb));
-void em28xx_uninit_isoc(struct em28xx *dev);
+void em28xx_uninit_isoc(struct em28xx *dev, enum em28xx_mode mode);
 int em28xx_isoc_dvb_max_packetsize(struct em28xx *dev);
 int em28xx_set_mode(struct em28xx *dev, enum em28xx_mode set_mode);
 int em28xx_gpio_set(struct em28xx *dev, struct em28xx_reg_seq *gpio);