Commit dfee02ac authored by Guido Kiener's avatar Guido Kiener Committed by Greg Kroah-Hartman
Browse files

usb: usbtmc: Fix ioctl USBTMC_IOCTL_CLEAR 



Remove calculation of max_size (=wMaxPacketSize) and wrong
condition (actual == max_size) in while loop. A device clear
should always flush the complete Bulk-IN FIFO.

Insert a sleep of 50 ms between subsequent CHECK_CLEAR_STATUS
control requests to avoid stressing the instrument with
repeated requests.

Some instruments need time to cleanup internal I/O buffers.
Polling and nonbraked requests slow down the response time of
devices.

Use USBTMC_BUFSIZE (4k) instead of USBTMC_SIZE_IOBUFFER (2k).
Using USBTMC_SIZE_IOBUFFER is deprecated.

Check only bit 0 (field bmClear) of the CHECK_CLEAR_STATUS
response, since other bits are reserved and can change in
future versions.

Signed-off-by: default avatarGuido Kiener <guido.kiener@rohde-schwarz.com>
Reviewed-by: default avatarSteve Bayless <steve_bayless@keysight.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d7604ff0

drivers/usb/class/usbtmc.c

+18 −28
Original line number Diff line number Diff line
@@ -1632,20 +1632,17 @@ exit: 


static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)

{

	struct usb_host_interface *current_setting;

	struct usb_endpoint_descriptor *desc;

	struct device *dev;

	u8 *buffer;

	int rv;

	int n;

	int actual = 0;

	int max_size;



	dev = &data->intf->dev;



	dev_dbg(dev, "Sending INITIATE_CLEAR request\n");



	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);

	buffer = kmalloc(USBTMC_BUFSIZE, GFP_KERNEL);

	if (!buffer)

		return -ENOMEM;
@@ -1653,7 +1650,7 @@ static int usbtmc_ioctl_clear(struct usbtmc_device_data *data) 
			     usb_rcvctrlpipe(data->usb_dev, 0),

			     USBTMC_REQUEST_INITIATE_CLEAR,

			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,

			     0, 0, buffer, 1, USBTMC_TIMEOUT);

			     0, 0, buffer, 1, USB_CTRL_GET_TIMEOUT);

	if (rv < 0) {

		dev_err(dev, "usb_control_msg returned %d\n", rv);

		goto exit;
@@ -1667,22 +1664,6 @@ static int usbtmc_ioctl_clear(struct usbtmc_device_data *data) 
		goto exit;

	}



	max_size = 0;

	current_setting = data->intf->cur_altsetting;

	for (n = 0; n < current_setting->desc.bNumEndpoints; n++) {

		desc = &current_setting->endpoint[n].desc;

		if (desc->bEndpointAddress == data->bulk_in)

			max_size = usb_endpoint_maxp(desc);

	}



	if (max_size == 0) {

		dev_err(dev, "Couldn't get wMaxPacketSize\n");

		rv = -EPERM;

		goto exit;

	}



	dev_dbg(dev, "wMaxPacketSize is %d\n", max_size);



	n = 0;



usbtmc_clear_check_status:
@@ -1693,7 +1674,7 @@ usbtmc_clear_check_status: 
			     usb_rcvctrlpipe(data->usb_dev, 0),

			     USBTMC_REQUEST_CHECK_CLEAR_STATUS,

			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,

			     0, 0, buffer, 2, USBTMC_TIMEOUT);

			     0, 0, buffer, 2, USB_CTRL_GET_TIMEOUT);

	if (rv < 0) {

		dev_err(dev, "usb_control_msg returned %d\n", rv);

		goto exit;
@@ -1710,15 +1691,19 @@ usbtmc_clear_check_status: 
		goto exit;

	}



	if (buffer[1] == 1)

	if ((buffer[1] & 1) != 0) {

		do {

			dev_dbg(dev, "Reading from bulk in EP\n");



			rv = usb_bulk_msg(data->usb_dev,

					  usb_rcvbulkpipe(data->usb_dev,

							  data->bulk_in),

					  buffer, USBTMC_SIZE_IOBUFFER,

					  &actual, USBTMC_TIMEOUT);

					  buffer, USBTMC_BUFSIZE,

					  &actual, USB_CTRL_GET_TIMEOUT);



			print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE,

					     16, 1, buffer, actual, true);



			n++;



			if (rv < 0) {
@@ -1726,10 +1711,15 @@ usbtmc_clear_check_status: 
					rv);

				goto exit;

			}

		} while ((actual == max_size) &&

		} while ((actual == USBTMC_BUFSIZE) &&

			  (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));

	} else {

		/* do not stress device with subsequent requests */

		msleep(50);

		n++;

	}



	if (actual == max_size) {

	if (n >= USBTMC_MAX_READS_TO_CLEAR_BULK_IN) {

		dev_err(dev, "Couldn't clear device buffer within %d cycles\n",

			USBTMC_MAX_READS_TO_CLEAR_BULK_IN);

		rv = -EPERM;
@@ -1743,7 +1733,7 @@ usbtmc_clear_bulk_out_halt: 
	rv = usb_clear_halt(data->usb_dev,

			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));

	if (rv < 0) {

		dev_err(dev, "usb_control_msg returned %d\n", rv);

		dev_err(dev, "usb_clear_halt returned %d\n", rv);

		goto exit;

	}

	rv = 0;

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