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authorGuido Kiener <guido@kiener-muenchen.de>2018-09-12 10:51:03 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-20 13:04:02 +0200
commitdfee02ac4bce6374c9769fe31f20794309341fa0 (patch)
tree5f924c7ac748180382df93fcbd5e4c16f17e0e29 /drivers/usb/class/usbtmc.c
parentusb: usbtmc: Optimize usbtmc_read (diff)
downloadlinux-dfee02ac4bce6374c9769fe31f20794309341fa0.tar.xz
linux-dfee02ac4bce6374c9769fe31f20794309341fa0.zip
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: Guido Kiener <guido.kiener@rohde-schwarz.com> Reviewed-by: Steve Bayless <steve_bayless@keysight.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/class/usbtmc.c')
-rw-r--r--drivers/usb/class/usbtmc.c46
1 files changed, 18 insertions, 28 deletions
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 26a779d0c89b..11b2c8632d91 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -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;