On Fri, 10 May 2019, Jim Lin wrote:
> The Clear_TT_Buffer request sent to the hub includes the address of
> the LS/FS child device in wValue field. usb_hub_clear_tt_buffer()
> uses udev->devnum to set the address wValue. This won't work for
> devices connected to xHC.
>
> For other host controllers udev->devnum is the same as the address of
> the usb device, chosen and set by usb core. With xHC the controller
> hardware assigns the address, and won't be the same as devnum.
>
> Here we add devaddr in "struct usb_device" for
> usb_hub_clear_tt_buffer() to use.
>
> Signed-off-by: Jim Lin <jilin@xxxxxxxxxx>
> ---
> v2: xhci_clear_tt_buffer_complete: add static, shorter indentation
> , remove its claiming in xhci.h
> v3: Add description for clearing_tt (xhci.h)
> v4: Remove clearing_tt flag because hub_tt_work has hub->tt.lock
> to protect for Clear_TT_Buffer to be run serially.
> Remove xhci_clear_tt_buffer_complete as it's not necessary.
> Same reason as the above.
> Extend usb_hub_clear_tt_buffer parameter
> v5: Not extending usb_hub_clear_tt_buffer parameter
> Add description.
> v6: Remove unused parameter slot_id from xhci_clear_hub_tt_buffer
> v7: Add devaddr field in "struct usb_device"
> v8: split as two patches, change type from int to u8 for devaddr.
> v9: Use pahole to find place to put devaddr in struct usb_device.
> Remove space between type cast and variable.
> hub.c changed from v8
> clear->devinfo |= (u16) (udev->devaddr << 4);
> to
> clear->devinfo |= ((u16)udev->devaddr) << 4;
> to solve a problem if devaddr is larger than 16.
>
>
> drivers/usb/core/hub.c | 4 +++-
> include/linux/usb.h | 2 ++
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 15a2934dc29d..0d4b289be103 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -873,7 +873,7 @@ int usb_hub_clear_tt_buffer(struct urb *urb)
> /* info that CLEAR_TT_BUFFER needs */
> clear->tt = tt->multi ? udev->ttport : 1;
> clear->devinfo = usb_pipeendpoint (pipe);
> - clear->devinfo |= udev->devnum << 4;
> + clear->devinfo |= ((u16)udev->devaddr) << 4;
> clear->devinfo |= usb_pipecontrol(pipe)
> ? (USB_ENDPOINT_XFER_CONTROL << 11)
> : (USB_ENDPOINT_XFER_BULK << 11);
> @@ -2125,6 +2125,8 @@ static void update_devnum(struct usb_device *udev, int devnum)
> /* The address for a WUSB device is managed by wusbcore. */
> if (!udev->wusb)
> udev->devnum = devnum;
> + if (!udev->devaddr)
> + udev->devaddr = (u8)devnum;
Whether or not to put a space after the ')' in a typecast is a matter
of personal choice; CodingStyle doesn't say anything about it. Quite
often the space is present. IIRC, that is how K&R does it. But it
doesn't really matter.
> }
>
> static void hub_free_dev(struct usb_device *udev)
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 4229eb74bd2c..5641965e44a1 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -566,6 +566,7 @@ struct usb3_lpm_parameters {
> * @tt: Transaction Translator info; used with low/full speed dev, highspeed hub
> * @ttport: device port on that tt hub
> * @toggle: one bit for each endpoint, with ([0] = IN, [1] = OUT) endpoints
> + * @devaddr: device address, XHCI: assigned by HW, others: same as devnum
> * @parent: our hub, unless we're the root
> * @bus: bus we're part of
> * @ep0: endpoint 0 data (default control pipe)
> @@ -643,6 +644,7 @@ struct usb_device {
> int ttport;
>
> unsigned int toggle[2];
> + u8 devaddr;
This is another lousy place to put the new value. A much better
position would be immediately after "u8 level".
> struct usb_device *parent;
> struct usb_bus *bus;
You should move into this patch the code added to xhci.c to assign
udev->devaddr. Without it, this patch is incomplete: devaddr will not
contain the correct value for devices on a USB-3 bus. And it doesn't
belong in the 2/2 patch -- that patch is all about making xhci-hcd call
usb_clear_tt_buffer().
Alan Stern
