Re: Reboot resistant USB bug

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

On Thu, Oct 11, 2018 at 02:11:22PM +0000, Emmanuel Dreyfus wrote:
> On both netbsd-8 and -current, I have a problem with USB devices that
> get stuck in a non-functionning state even after a reboot.

I investigated a lot: in my example, the pn533 chip seems to corrupts
its USB config, interface and endpoint descriptors. They contain 
garbage, and on reboot the kernel cannot figure enough  about the 
device, and disable the USB port.

But if I detect the condition in usbd_get_desc() and inject
fake descriptors (see below), the device is correctly attached
on reboot, and it works again. Is it an acceptable workaround?

usbd_status
usbd_get_desc(struct usbd_device *dev, int type, int index, int len, void *desc)
{
        usb_device_request_t req;
        usbd_status err;

        USBHIST_FUNC(); USBHIST_CALLED(usbdebug);

        DPRINTFN(3,"type=%jd, index=%jd, len=%jd", type, index, len, 0);

        req.bmRequestType = UT_READ_DEVICE;
        req.bRequest = UR_GET_DESCRIPTOR;
        USETW2(req.wValue, type, index);
        USETW(req.wIndex, 0);
        USETW(req.wLength, len);
        err = usbd_do_request(dev, &req, desc);

        /*
         * Attempt to fake the descriptor if it fails sanity check
         */
        if (err == USBD_NORMAL_COMPLETION) {
                usb_descriptor_t *d = desc;

                if (d->bDescriptorType != type || d->bLength > len)
                        err = usbd_get_desc_fake(dev, type, index, len, desc);
        }

        return err;
}


-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost