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Commit f5001928 authored by Andrey Shvetsov's avatar Andrey Shvetsov Committed by Greg Kroah-Hartman
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staging: most: usb: fix calculation of the extra_len 



The final size of the buffer used for the streaming transfer consists of
the size for the user payload (buffer_size) and the size for the gaps
needed by the controller (extra_len).

The current implementation of the hdm_configure_channel() corrects the
buffer size down to the next appropriate for the hardware value, that is
the whole number of frames, but uses the old unaligned value to
calculate the extra_len.

Current patch fixes the described problem.

Signed-off-by: default avatarAndrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: default avatarChristian Gromm <christian.gromm@microchip.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2c4aaa1f

drivers/staging/most/hdm-usb/hdm_usb.c

+9 −18
Original line number Diff line number Diff line
@@ -649,8 +649,6 @@ static int hdm_configure_channel(struct most_interface *iface, int channel, 
{

	unsigned int num_frames;

	unsigned int frame_size;

	unsigned int temp_size;

	unsigned int tail_space;

	struct most_dev *mdev = to_mdev(iface);

	struct device *dev = &mdev->usb_device->dev;
@@ -685,7 +683,6 @@ static int hdm_configure_channel(struct most_interface *iface, int channel, 
	}



	mdev->padding_active[channel] = true;

	temp_size = conf->buffer_size;



	frame_size = get_stream_frame_size(conf);

	if (frame_size == 0 || frame_size > USB_MTU) {
@@ -693,25 +690,19 @@ static int hdm_configure_channel(struct most_interface *iface, int channel, 
		return -EINVAL;

	}



	num_frames = conf->buffer_size / frame_size;



	if (conf->buffer_size % frame_size) {

		u16 tmp_val;

		u16 old_size = conf->buffer_size;



		tmp_val = conf->buffer_size / frame_size;

		conf->buffer_size = tmp_val * frame_size;

		dev_notice(dev,

			   "Channel %d - rounding buffer size to %d bytes, channel config says %d bytes\n",

			   channel,

			   conf->buffer_size,

			   temp_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);

	}



	num_frames = conf->buffer_size / frame_size;

	tail_space = num_frames * (USB_MTU - frame_size);

	temp_size += tail_space;



	/* calculate extra length to comply w/ HW padding */

	conf->extra_len = (DIV_ROUND_UP(temp_size, USB_MTU) * USB_MTU)

			  - conf->buffer_size;

	conf->extra_len = num_frames * (USB_MTU - frame_size);



exit:

	mdev->conf[channel] = *conf;

	if (conf->data_type == MOST_CH_ASYNC) {