[media] em28xx-audio: split URB initialization code
The URB calculus code may eventually be moved to some other place, like at pcm open, if it ends by needing more setups, like working with different bit rates, or different audio latency. So, move it into a separate routine. That also makes the code more readable. No functional changes. Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Mauro Carvalho Chehab
parent
34906633fa
commit
966f416375
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@ -681,17 +681,154 @@ static int em28xx_audio_ep_packet_size(struct usb_device *udev,
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return size & 0x7ff;
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}
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static int em28xx_audio_urb_init(struct em28xx *dev)
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{
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struct usb_interface *intf;
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struct usb_endpoint_descriptor *e, *ep = NULL;
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int i, ep_size, interval, num_urb, npackets;
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int urb_size, bytes_per_transfer;
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u8 alt;
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if (dev->audio_ifnum)
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alt = 1;
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else
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alt = 7;
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intf = usb_ifnum_to_if(dev->udev, dev->audio_ifnum);
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if (intf->num_altsetting <= alt) {
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em28xx_errdev("alt %d doesn't exist on interface %d\n",
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dev->audio_ifnum, alt);
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return -ENODEV;
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}
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for (i = 0; i < intf->altsetting[alt].desc.bNumEndpoints; i++) {
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e = &intf->altsetting[alt].endpoint[i].desc;
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if (!usb_endpoint_dir_in(e))
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continue;
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if (e->bEndpointAddress == EM28XX_EP_AUDIO) {
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ep = e;
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break;
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}
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}
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if (!ep) {
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em28xx_errdev("Couldn't find an audio endpoint");
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return -ENODEV;
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}
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ep_size = em28xx_audio_ep_packet_size(dev->udev, ep);
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interval = 1 << (ep->bInterval - 1);
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em28xx_info("Endpoint 0x%02x %s on intf %d alt %d interval = %d, size %d\n",
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EM28XX_EP_AUDIO, usb_speed_string(dev->udev->speed),
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dev->audio_ifnum, alt,
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interval,
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ep_size);
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/* Calculate the number and size of URBs to better fit the audio samples */
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/*
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* Estimate the number of bytes per DMA transfer.
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*
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* This is given by the bit rate (for now, only 48000 Hz) multiplied
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* by 2 channels and 2 bytes/sample divided by the number of microframe
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* intervals and by the microframe rate (125 us)
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*/
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bytes_per_transfer = DIV_ROUND_UP(48000 * 2 * 2, 125 * interval);
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/*
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* Estimate the number of transfer URBs. Don't let it go past the
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* maximum number of URBs that is known to be supported by the device.
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*/
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num_urb = DIV_ROUND_UP(bytes_per_transfer, ep_size);
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if (num_urb > EM28XX_MAX_AUDIO_BUFS)
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num_urb = EM28XX_MAX_AUDIO_BUFS;
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/*
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* Now that we know the number of bytes per transfer and the number of
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* URBs, estimate the typical size of an URB, in order to adjust the
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* minimal number of packets.
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*/
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urb_size = bytes_per_transfer / num_urb;
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/*
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* Now, calculate the amount of audio packets to be filled on each
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* URB. In order to preserve the old behaviour, use a minimal
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* threshold for this value.
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*/
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npackets = EM28XX_MIN_AUDIO_PACKETS;
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if (urb_size > ep_size * npackets)
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npackets = DIV_ROUND_UP(urb_size, ep_size);
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em28xx_info("Number of URBs: %d, with %d packets and %d size",
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num_urb, npackets, urb_size);
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/* Allocate space to store the number of URBs to be used */
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dev->adev.transfer_buffer = kcalloc(num_urb,
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sizeof(*dev->adev.transfer_buffer),
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GFP_ATOMIC);
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if (!dev->adev.transfer_buffer) {
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return -ENOMEM;
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}
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dev->adev.urb = kcalloc(num_urb, sizeof(*dev->adev.urb), GFP_ATOMIC);
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if (!dev->adev.urb) {
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kfree(dev->adev.transfer_buffer);
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return -ENOMEM;
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}
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/* Alloc memory for each URB and for each transfer buffer */
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dev->adev.num_urb = num_urb;
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for (i = 0; i < num_urb; i++) {
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struct urb *urb;
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int j, k;
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void *buf;
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urb = usb_alloc_urb(npackets, GFP_ATOMIC);
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if (!urb) {
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em28xx_errdev("usb_alloc_urb failed!\n");
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em28xx_audio_free_urb(dev);
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return -ENOMEM;
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}
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dev->adev.urb[i] = urb;
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buf = usb_alloc_coherent(dev->udev, npackets * ep_size, GFP_ATOMIC,
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&urb->transfer_dma);
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if (!buf) {
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em28xx_errdev("usb_alloc_coherent failed!\n");
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em28xx_audio_free_urb(dev);
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return -ENOMEM;
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}
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dev->adev.transfer_buffer[i] = buf;
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urb->dev = dev->udev;
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urb->context = dev;
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urb->pipe = usb_rcvisocpipe(dev->udev, EM28XX_EP_AUDIO);
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urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
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urb->transfer_buffer = buf;
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urb->interval = interval;
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urb->complete = em28xx_audio_isocirq;
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urb->number_of_packets = npackets;
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urb->transfer_buffer_length = ep_size * npackets;
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for (j = k = 0; j < npackets; j++, k += ep_size) {
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urb->iso_frame_desc[j].offset = k;
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urb->iso_frame_desc[j].length = ep_size;
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}
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}
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return 0;
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}
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static int em28xx_audio_init(struct em28xx *dev)
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{
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struct em28xx_audio *adev = &dev->adev;
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struct snd_pcm *pcm;
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struct snd_card *card;
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struct usb_interface *intf;
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struct usb_endpoint_descriptor *e, *ep = NULL;
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static int devnr;
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int err, i, ep_size, interval, num_urb, npackets;
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int urb_size, bytes_per_transfer;
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u8 alt;
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int err;
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if (!dev->has_alsa_audio || dev->audio_ifnum < 0) {
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/* This device does not support the extension (in this case
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@ -750,142 +887,12 @@ static int em28xx_audio_init(struct em28xx *dev)
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em28xx_cvol_new(card, dev, "Surround", AC97_SURROUND_MASTER);
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}
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if (dev->audio_ifnum)
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alt = 1;
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else
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alt = 7;
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intf = usb_ifnum_to_if(dev->udev, dev->audio_ifnum);
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if (intf->num_altsetting <= alt) {
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em28xx_errdev("alt %d doesn't exist on interface %d\n",
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dev->audio_ifnum, alt);
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err = em28xx_audio_urb_init(dev);
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if (err) {
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snd_card_free(card);
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return -ENODEV;
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}
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for (i = 0; i < intf->altsetting[alt].desc.bNumEndpoints; i++) {
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e = &intf->altsetting[alt].endpoint[i].desc;
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if (!usb_endpoint_dir_in(e))
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continue;
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if (e->bEndpointAddress == EM28XX_EP_AUDIO) {
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ep = e;
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break;
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}
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}
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if (!ep) {
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em28xx_errdev("Couldn't find an audio endpoint");
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snd_card_free(card);
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return -ENODEV;
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}
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ep_size = em28xx_audio_ep_packet_size(dev->udev, ep);
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interval = 1 << (ep->bInterval - 1);
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em28xx_info("Endpoint 0x%02x %s on intf %d alt %d interval = %d, size %d\n",
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EM28XX_EP_AUDIO, usb_speed_string(dev->udev->speed),
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dev->audio_ifnum, alt,
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interval,
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ep_size);
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/* Calculate the number and size of URBs to better fit the audio samples */
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/*
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* Estimate the number of bytes per DMA transfer.
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*
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* This is given by the bit rate (for now, only 48000 Hz) multiplied
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* by 2 channels and 2 bytes/sample divided by the number of microframe
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* intervals and by the microframe rate (125 us)
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*/
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bytes_per_transfer = DIV_ROUND_UP(48000 * 2 * 2, 125 * interval);
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/*
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* Estimate the number of transfer URBs. Don't let it go past the
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* maximum number of URBs that is known to be supported by the device.
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*/
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num_urb = DIV_ROUND_UP(bytes_per_transfer, ep_size);
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if (num_urb > EM28XX_MAX_AUDIO_BUFS)
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num_urb = EM28XX_MAX_AUDIO_BUFS;
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/*
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* Now that we know the number of bytes per transfer and the number of
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* URBs, estimate the typical size of an URB, in order to adjust the
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* minimal number of packets.
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*/
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urb_size = bytes_per_transfer / num_urb;
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/*
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* Now, calculate the amount of audio packets to be filled on each
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* URB. In order to preserve the old behaviour, use a minimal
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* threshold for this value.
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*/
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npackets = EM28XX_MIN_AUDIO_PACKETS;
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if (urb_size > ep_size * npackets)
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npackets = DIV_ROUND_UP(urb_size, ep_size);
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em28xx_info("Number of URBs: %d, with %d packets and %d size",
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num_urb, npackets, urb_size);
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/* Allocate space to store the number of URBs to be used */
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dev->adev.transfer_buffer = kcalloc(num_urb,
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sizeof(*dev->adev.transfer_buffer),
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GFP_ATOMIC);
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if (!dev->adev.transfer_buffer) {
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snd_card_free(card);
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return -ENOMEM;
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}
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dev->adev.urb = kcalloc(num_urb, sizeof(*dev->adev.urb), GFP_ATOMIC);
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if (!dev->adev.urb) {
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snd_card_free(card);
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kfree(dev->adev.transfer_buffer);
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return -ENOMEM;
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}
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/* Alloc memory for each URB and for each transfer buffer */
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dev->adev.num_urb = num_urb;
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for (i = 0; i < num_urb; i++) {
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struct urb *urb;
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int j, k;
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void *buf;
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urb = usb_alloc_urb(npackets, GFP_ATOMIC);
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if (!urb) {
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em28xx_errdev("usb_alloc_urb failed!\n");
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em28xx_audio_free_urb(dev);
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snd_card_free(card);
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return -ENOMEM;
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}
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dev->adev.urb[i] = urb;
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buf = usb_alloc_coherent(dev->udev, npackets * ep_size, GFP_ATOMIC,
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&urb->transfer_dma);
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if (!buf) {
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em28xx_errdev("usb_alloc_coherent failed!\n");
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em28xx_audio_free_urb(dev);
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snd_card_free(card);
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return -ENOMEM;
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}
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dev->adev.transfer_buffer[i] = buf;
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urb->dev = dev->udev;
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urb->context = dev;
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urb->pipe = usb_rcvisocpipe(dev->udev, EM28XX_EP_AUDIO);
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urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
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urb->transfer_buffer = buf;
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urb->interval = interval;
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urb->complete = em28xx_audio_isocirq;
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urb->number_of_packets = npackets;
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urb->transfer_buffer_length = ep_size * npackets;
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for (j = k = 0; j < npackets; j++, k += ep_size) {
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urb->iso_frame_desc[j].offset = k;
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urb->iso_frame_desc[j].length = ep_size;
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}
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}
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err = snd_card_register(card);
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if (err < 0) {
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em28xx_audio_free_urb(dev);
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