[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>

1 files changed, 96 insertions, 49 deletions

diff --git a/drivers/media/video/em28xx/em28xx-core.c b/drivers/media/video/em28xx/em28xx-core.c
index 0aacc96f9a23..53a9fb91e97e 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/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;
 		}
 	}