Author: hselasky
Date: Thu Oct 8 11:30:22 2020
New Revision: 366536
URL: https://svnweb.freebsd.org/changeset/base/366536
Log:
Try a bit harder to get the USB device descriptor in case the initial read
fails.
MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking
Modified:
head/sys/dev/usb/usb_request.c
Modified: head/sys/dev/usb/usb_request.c
==============================================================================
--- head/sys/dev/usb/usb_request.c Thu Oct 8 11:25:19 2020
(r366535)
+++ head/sys/dev/usb/usb_request.c Thu Oct 8 11:30:22 2020
(r366536)
@@ -1973,9 +1973,23 @@ usbd_setup_device_desc(struct usb_device *udev, struct
/* get partial device descriptor, some devices crash on this */
err = usbd_req_get_desc(udev, mtx, NULL, &udev->ddesc,
USB_MAX_IPACKET, USB_MAX_IPACKET, 0, UDESC_DEVICE, 0, 0);
- if (err != 0)
- break;
-
+ if (err != 0) {
+ DPRINTF("Trying fallback for getting the USB device
descriptor\n");
+ /* try 8 bytes bMaxPacketSize */
+ udev->ddesc.bMaxPacketSize = 8;
+ /* get full device descriptor */
+ err = usbd_req_get_device_desc(udev, mtx, &udev->ddesc);
+ if (err == 0)
+ break;
+ /* try 16 bytes bMaxPacketSize */
+ udev->ddesc.bMaxPacketSize = 16;
+ /* get full device descriptor */
+ err = usbd_req_get_device_desc(udev, mtx, &udev->ddesc);
+ if (err == 0)
+ break;
+ /* try 32/64 bytes bMaxPacketSize */
+ udev->ddesc.bMaxPacketSize = 32;
+ }
/* get the full device descriptor */
err = usbd_req_get_device_desc(udev, mtx, &udev->ddesc);
break;
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