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usb: usbtmc: Fix ioctl USBTMC_IOCTL_CLEAR

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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: Guido Kiener <guido.kiener@rohde-schwarz.com>
Reviewed-by: Steve Bayless <steve_bayless@keysight.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Guido Kiener 2018-09-12 10:51:03 +02:00 committed by Greg Kroah-Hartman
parent d7604ff0dc
commit dfee02ac4b
1 changed files with 18 additions and 28 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

46
drivers/usb/class/usbtmc.c
View file

@ -1632,20 +1632,17 @@ static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
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 @@ static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
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 @@ static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
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 @@ static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
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 @@ static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
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;