static int hdm_configure_channel()

in most_usb.c [566:635]

• 52 lines of code
• 13 McCabe index (conditional complexity)

static int hdm_configure_channel(struct most_interface *iface, int channel,
				 struct most_channel_config *conf)
{
	unsigned int num_frames;
	unsigned int frame_size;
	struct most_dev *mdev = to_mdev(iface);
	struct device *dev = &mdev->usb_device->dev;

	if (!conf) {
		dev_err(dev, "Bad config pointer.\n");
		return -EINVAL;
	}
	if (channel < 0 || channel >= iface->num_channels) {
		dev_err(dev, "Channel ID out of range.\n");
		return -EINVAL;
	}

	mdev->is_channel_healthy[channel] = true;
	mdev->clear_work[channel].channel = channel;
	mdev->clear_work[channel].mdev = mdev;
	INIT_WORK(&mdev->clear_work[channel].ws, wq_clear_halt);

	if (!conf->num_buffers || !conf->buffer_size) {
		dev_err(dev, "Misconfig: buffer size or #buffers zero.\n");
		return -EINVAL;
	}

	if (conf->data_type != MOST_CH_SYNC &&
	    !(conf->data_type == MOST_CH_ISOC &&
	      conf->packets_per_xact != 0xFF)) {
		mdev->padding_active[channel] = false;
		/*
		 * Since the NIC's padding mode is not going to be
		 * used, we can skip the frame size calculations and
		 * move directly on to exit.
		 */
		goto exit;
	}

	mdev->padding_active[channel] = true;

	frame_size = get_stream_frame_size(&mdev->dev, conf);
	if (frame_size == 0 || frame_size > USB_MTU) {
		dev_warn(dev, "Misconfig: frame size wrong\n");
		return -EINVAL;
	}

	num_frames = conf->buffer_size / frame_size;

	if (conf->buffer_size % frame_size) {
		u16 old_size = conf->buffer_size;

		conf->buffer_size = num_frames * frame_size;
		dev_warn(dev, "%s: fixed buffer size (%d -> %d)\n",
			 mdev->suffix[channel], old_size, conf->buffer_size);
	}

	/* calculate extra length to comply w/ HW padding */
	conf->extra_len = num_frames * (USB_MTU - frame_size);

exit:
	mdev->conf[channel] = *conf;
	if (conf->data_type == MOST_CH_ASYNC) {
		u16 ep = mdev->ep_address[channel];

		if (start_sync_ep(mdev->usb_device, ep) < 0)
			dev_warn(dev, "sync for ep%02x failed", ep);
	}
	return 0;
}