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.kie...@rohde-schwarz.com>
Reviewed-by: Steve Bayless <steve_bayl...@keysight.com>
---
drivers/usb/class/usbtmc.c | 46 +++++++++++++++-----------------------
1 file changed, 18 insertions(+), 28 deletions(-)
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index fa8b17947792..dda5391d01e5 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -1700,20 +1700,17 @@ 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;
@@ -1721,7 +1718,7 @@ 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;
@@ -1735,22 +1732,6 @@ 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 = ¤t_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:
@@ -1761,7 +1742,7 @@ 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;
@@ -1778,15 +1759,19 @@ 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) {
@@ -1794,10 +1779,15 @@ 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;
@@ -1811,7 +1801,7 @@ 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;
--
2.17.1
--
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