Re: kern/46696 (uhub disables port where USB keyboard attached)

[Nick Hudson <skrll%netbsd.org@localhost>]

The following reply was made to PR kern/46696; it has been noted by GNATS.

From: Nick Hudson <skrll%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: skrll%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, 
netbsd-bugs%netbsd.org@localhost, 
 gnats-admin%netbsd.org@localhost, mishka%NetBSD.org@localhost, 
kato%wide.ad.jp@localhost, 
 Andreas Gustafsson <gson%gson.org@localhost>
Subject: Re: kern/46696 (uhub disables port where USB keyboard attached)
Date: Thu, 12 Sep 2013 10:05:40 +0100

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 Can you test today's -current again and then try -current with this 
 patch and report results.
 
 Thanks,
 Nick
 
 
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 Index: sys/dev/usb/usb_subr.c
 ===================================================================
 RCS file: /cvsroot/src/sys/dev/usb/usb_subr.c,v
 retrieving revision 1.192
 diff -u -p -r1.192 usb_subr.c
 --- sys/dev/usb/usb_subr.c     7 Sep 2013 16:39:15 -0000       1.192
 +++ sys/dev/usb/usb_subr.c     12 Sep 2013 09:01:29 -0000
 @@ -1059,34 +1059,6 @@ usbd_reattach_device(device_t parent, us
  }
  
  /*
 - * Get the first 8 bytes of the device descriptor.
 - * Do as Windows does: try to read 64 bytes -- there are devices which
 - * recognize the initial descriptor fetch (before the control endpoint's
 - * MaxPacketSize is known by the host) by exactly this length.
 - */
 -static usbd_status
 -usbd_get_initial_ddesc(usbd_device_handle dev, usb_device_descriptor_t *desc)
 -{
 -      usb_device_request_t req;
 -      char buf[64];
 -      int res, actlen;
 -
 -      req.bmRequestType = UT_READ_DEVICE;
 -      req.bRequest = UR_GET_DESCRIPTOR;
 -      USETW2(req.wValue, UDESC_DEVICE, 0);
 -      USETW(req.wIndex, 0);
 -      USETW(req.wLength, 64);
 -      res = usbd_do_request_flags(dev, &req, buf, USBD_SHORT_XFER_OK,
 -              &actlen, USBD_DEFAULT_TIMEOUT);
 -      if (res)
 -              return res;
 -      if (actlen < 8)
 -              return USBD_SHORT_XFER;
 -      memcpy(desc, buf, 8);
 -      return USBD_NORMAL_COMPLETION;
 -}
 -
 -/*
   * Called when a new device has been put in the powered state,
   * but not yet in the addressed state.
   * Get initial descriptor, set the address, get full descriptor,
 @@ -1130,7 +1102,6 @@ usbd_new_device(device_t parent, usbd_bu
        dev->def_ep_desc.bmAttributes = UE_CONTROL;
        /*
         * temporary, will be fixed after first descriptor fetch
 -       * (which uses 64 bytes so it shouldn't be less),
         * highspeed devices must support 64 byte packets anyway
         */
        if (speed == USB_SPEED_HIGH || speed == USB_SPEED_FULL)
 @@ -1183,14 +1154,44 @@ usbd_new_device(device_t parent, usbd_bu
        }
  
        dd = &dev->ddesc;
 -      /* Try a few times in case the device is slow (i.e. outside specs.) */
 -      for (i = 0; i < 10; i++) {
 -              /* Get the first 8 bytes of the device descriptor. */
 -              err = usbd_get_initial_ddesc(dev, dd);
 +
 +      /*
 +       * Get the first 8 bytes of the device descriptor.
 +       *
 +       * Try a few times in case the device is slow (i.e. outside specs.),
 +       * and alternate between read lengths.
 +       *
 +       * Do as Windows does: try to read 64 bytes -- there are devices
 +       * which recognize the initial descriptor fetch (before the
 +       * control endpoint's MaxPacketSize is known by the host) by
 +       * exactly this length.
 +       *
 +       * If this doesn't work, then attempt to read just the 8 bytes.
 +       *
 +       * Throw in a reset after 3 read attempts so that the device
 +       * will see an initial read after reset of both 64 and 8 over
 +       * time.
 +       */
 +      for (i = 0; i < 12; i++) {
 +              usb_device_request_t req;
 +              char buf[64];
 +              int actlen;
 +
 +              req.bmRequestType = UT_READ_DEVICE;
 +              req.bRequest = UR_GET_DESCRIPTOR;
 +              USETW2(req.wValue, UDESC_DEVICE, 0);
 +              USETW(req.wIndex, 0);
 +              USETW(req.wLength, (i % 2 == 0 ? 64 : 8));
 +              err = usbd_do_request_flags(dev, &req, buf, USBD_SHORT_XFER_OK,
 +                      &actlen, USBD_DEFAULT_TIMEOUT);
 +              if (actlen < 8)
 +                      continue;
 +              memcpy(dd, buf, 8);
 +
                if (!err)
                        break;
                usbd_delay_ms(dev, 200);
 -              if ((i & 3) == 3)
 +              if ((i % 3) == 2)
                        usbd_reset_port(up->parent, port, &ps);
        }
        if (err) {
 
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