Author: hselasky
Date: Wed Jun 27 12:08:12 2018
New Revision: 335700
URL: https://svnweb.freebsd.org/changeset/base/335700
Log:
Improve the kernel's USB descriptor reading function.
Some USB devices does not allow a partial descriptor readout.
Found by: bz@
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/sys/dev/usb/usb_request.c
Modified: head/sys/dev/usb/usb_request.c
==============================================================================
--- head/sys/dev/usb/usb_request.c Wed Jun 27 07:24:07 2018
(r335699)
+++ head/sys/dev/usb/usb_request.c Wed Jun 27 12:08:12 2018
(r335700)
@@ -990,7 +990,7 @@ usbd_req_get_desc(struct usb_device *udev,
uint8_t retries)
{
struct usb_device_request req;
- uint8_t *buf;
+ uint8_t *buf = desc;
usb_error_t err;
DPRINTFN(4, "id=%d, type=%d, index=%d, max_len=%d\n",
@@ -1012,6 +1012,32 @@ usbd_req_get_desc(struct usb_device *udev,
err = usbd_do_request_flags(udev, mtx, &req,
desc, 0, NULL, 500 /* ms */);
+ if (err != 0 && err != USB_ERR_TIMEOUT &&
+ min_len != max_len) {
+ /* clear descriptor data */
+ memset(desc, 0, max_len);
+
+ /* try to read full descriptor length */
+ USETW(req.wLength, max_len);
+
+ err = usbd_do_request_flags(udev, mtx, &req,
+ desc, USB_SHORT_XFER_OK, NULL, 500 /* ms */);
+
+ if (err == 0) {
+ /* verify length */
+ if (buf[0] > max_len)
+ buf[0] = max_len;
+ else if (buf[0] < 2)
+ err = USB_ERR_INVAL;
+
+ min_len = buf[0];
+
+ /* enforce descriptor type */
+ buf[1] = type;
+ goto done;
+ }
+ }
+
if (err) {
if (!retries) {
goto done;
@@ -1022,7 +1048,6 @@ usbd_req_get_desc(struct usb_device *udev,
continue;
}
- buf = desc;
if (min_len == max_len) {
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