[PATCH] ALSA: usb/caiaq: use usb_buffer_alloc()

[Daniel Mack]

Use usb_buffer_alloc() and usb_buffer_free() for transfer buffers.
We need DMA-coherent memory in this case as buffer contents are likely
to be modified after the URB was submitted, because the URB buffers
are mapped to the audio streams.

On x86_64, buffers allocated with kmalloc() may be beyond the boundaries
of 32bit accessible memory, and DMA bounce buffers will live at other
locations, unaccessible by the driver, and hence outside of the audio
buffer mapping.

Signed-off-by: Daniel Mack <daniel at caiaq.de>
Tested-by: Pedro Ribeiro <pedrib at gmail.com>
Cc: Takashi Iwai <tiwai at suse.de>
Cc: Alan Stern <stern at rowland.harvard.edu>
Cc: Chris Wright <chrisw at sous-sol.org>
Cc: David Woodhouse <dwmw2 at infradead.org>
Cc: Andi Kleen <andi at firstfloor.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Greg KH <gregkh at suse.de>
Cc: iommu at lists.linux-foundation.org
Cc: Kernel development list <linux-kernel at vger.kernel.org>
Cc: USB list <linux-usb at vger.kernel.org>
Cc: stable at kernel.org
---
 sound/usb/caiaq/audio.c |   57 ++++++++++++++++++++++++++--------------------
 1 files changed, 32 insertions(+), 25 deletions(-)

diff --git a/sound/usb/caiaq/audio.c b/sound/usb/caiaq/audio.c
index 4328cad..adbeefd 100644
--- a/sound/usb/caiaq/audio.c
+++ b/sound/usb/caiaq/audio.c
@@ -552,46 +552,47 @@ static struct urb **alloc_urbs(struct snd_usb_caiaqdev *dev, int dir, int *ret)
 	}
 
 	for (i = 0; i < N_URBS; i++) {
-		urbs[i] = usb_alloc_urb(FRAMES_PER_URB, GFP_KERNEL);
-		if (!urbs[i]) {
+		struct urb *u = usb_alloc_urb(FRAMES_PER_URB, GFP_KERNEL);
+		if (!u) {
 			log("unable to usb_alloc_urb(), OOM!?\n");
 			*ret = -ENOMEM;
 			return urbs;
 		}
 
-		urbs[i]->transfer_buffer =
-			kmalloc(FRAMES_PER_URB * BYTES_PER_FRAME, GFP_KERNEL);
-		if (!urbs[i]->transfer_buffer) {
-			log("unable to kmalloc() transfer buffer, OOM!?\n");
+		urbs[i] = u;
+		u->dev = usb_dev;
+		u->pipe = pipe;
+		u->transfer_buffer_length =
+				FRAMES_PER_URB * BYTES_PER_FRAME;
+		u->context = &dev->data_cb_info[i];
+		u->interval = 1;
+		u->transfer_flags = URB_ISO_ASAP;
+		u->number_of_packets = FRAMES_PER_URB;
+		u->complete = (dir == SNDRV_PCM_STREAM_CAPTURE) ?
+					read_completed : write_completed;
+		u->transfer_buffer = usb_alloc_coherent(usb_dev,
+							u->transfer_buffer_length,
+							GFP_KERNEL, &u->transfer_dma);
+		if (!u->transfer_buffer) {
+			log("usb_alloc_coherent() failed, OOM!?\n");
 			*ret = -ENOMEM;
 			return urbs;
 		}
 
 		for (frame = 0; frame < FRAMES_PER_URB; frame++) {
 			struct usb_iso_packet_descriptor *iso =
-				&urbs[i]->iso_frame_desc[frame];
+					&u->iso_frame_desc[frame];
 
 			iso->offset = BYTES_PER_FRAME * frame;
 			iso->length = BYTES_PER_FRAME;
 		}
-
-		urbs[i]->dev = usb_dev;
-		urbs[i]->pipe = pipe;
-		urbs[i]->transfer_buffer_length = FRAMES_PER_URB
-						* BYTES_PER_FRAME;
-		urbs[i]->context = &dev->data_cb_info[i];
-		urbs[i]->interval = 1;
-		urbs[i]->transfer_flags = URB_ISO_ASAP;
-		urbs[i]->number_of_packets = FRAMES_PER_URB;
-		urbs[i]->complete = (dir == SNDRV_PCM_STREAM_CAPTURE) ?
-					read_completed : write_completed;
 	}
 
 	*ret = 0;
 	return urbs;
 }
 
-static void free_urbs(struct urb **urbs)
+static void free_urbs(struct usb_device *usb_dev, struct urb **urbs)
 {
 	int i;
 
@@ -603,7 +604,10 @@ static void free_urbs(struct urb **urbs)
 			continue;
 
 		usb_kill_urb(urbs[i]);
-		kfree(urbs[i]->transfer_buffer);
+		usb_free_coherent(usb_dev,
+				  urbs[i]->transfer_buffer_length,
+				  urbs[i]->transfer_buffer,
+				  urbs[i]->transfer_dma);
 		usb_free_urb(urbs[i]);
 	}
 
@@ -613,6 +617,7 @@ static void free_urbs(struct urb **urbs)
 int snd_usb_caiaq_audio_init(struct snd_usb_caiaqdev *dev)
 {
 	int i, ret;
+	struct usb_device *usb_dev = dev->chip.dev;
 
 	dev->n_audio_in  = max(dev->spec.num_analog_audio_in,
 			       dev->spec.num_digital_audio_in) /
@@ -689,15 +694,15 @@ int snd_usb_caiaq_audio_init(struct snd_usb_caiaqdev *dev)
 	dev->data_urbs_in = alloc_urbs(dev, SNDRV_PCM_STREAM_CAPTURE, &ret);
 	if (ret < 0) {
 		kfree(dev->data_cb_info);
-		free_urbs(dev->data_urbs_in);
+		free_urbs(usb_dev, dev->data_urbs_in);
 		return ret;
 	}
 
 	dev->data_urbs_out = alloc_urbs(dev, SNDRV_PCM_STREAM_PLAYBACK, &ret);
 	if (ret < 0) {
 		kfree(dev->data_cb_info);
-		free_urbs(dev->data_urbs_in);
-		free_urbs(dev->data_urbs_out);
+		free_urbs(usb_dev, dev->data_urbs_in);
+		free_urbs(usb_dev, dev->data_urbs_out);
 		return ret;
 	}
 
@@ -706,10 +711,12 @@ int snd_usb_caiaq_audio_init(struct snd_usb_caiaqdev *dev)
 
 void snd_usb_caiaq_audio_free(struct snd_usb_caiaqdev *dev)
 {
+	struct usb_device *usb_dev = dev->chip.dev;
+
 	debug("%s(%p)\n", __func__, dev);
 	stream_stop(dev);
-	free_urbs(dev->data_urbs_in);
-	free_urbs(dev->data_urbs_out);
+	free_urbs(usb_dev, dev->data_urbs_in);
+	free_urbs(usb_dev, dev->data_urbs_out);
 	kfree(dev->data_cb_info);
 }
 
-- 
1.7.1