With the upcoming input pipelining support, large input packets may get submitted to the device, which require special handling when the packets ends up being split again by usb-host-linux due to usbfs limitations. The exact demands for properly handling larger split input transfers is explained in detail in this libusb commit: https://github.com/libusbx/libusbx/commit/ede02ba91920f9be787a7f3cd006c5a4b92b5eab
Specifically in the large comment block the commit adds. Note that IMHO it would be better to just port usb-host-linux to libusb and let libusb worry about such usbfs details, rather then reproducing all this code inside host-linux.c Note that the not proper handling of this currently already can be a problem when used in combination with an emulated xhci controller, as that can already submit large enough transfers to trigger this. Signed-off-by: Hans de Goede <hdego...@redhat.com> --- hw/usb/host-linux.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/usb/host-linux.c b/hw/usb/host-linux.c index 44f1a64..3a258b4 100644 --- a/hw/usb/host-linux.c +++ b/hw/usb/host-linux.c @@ -1224,7 +1224,8 @@ static int usb_linux_update_endp_table(USBHostDevice *s) usb_ep_set_type(&s->dev, pid, ep, type); usb_ep_set_ifnum(&s->dev, pid, ep, interface); if ((s->options & (1 << USB_HOST_OPT_PIPELINE)) && - (type == USB_ENDPOINT_XFER_BULK)) { + (type == USB_ENDPOINT_XFER_BULK) && + (pid == USB_TOKEN_OUT)) { usb_ep_set_pipeline(&s->dev, pid, ep, true); } -- 1.7.12.1