Jason Andryuk, le jeu. 12 mars 2020 08:55:23 -0400, a ecrit: > Linux guests wait ~30 seconds when closing the emulated /dev/ttyUSB0. > During that time, the kernel driver is sending many control URBs > requesting GetModemStat (5). Real hardware returns a status with > FTDI_THRE (Transmitter Holding Register) and FTDI_TEMT (Transmitter > Empty) set. QEMU leaves them clear, and it seems Linux is waiting for > FTDI_TEMT to be set to indicate the tx queue is empty before closing. > > Set the bits when responding to a GetModemStat query and avoid the > shutdown delay. > > Signed-off-by: Jason Andryuk <jandr...@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thiba...@ens-lyon.org> > --- > Looking at a USB dump for a real FTDI USB adapter, I see these bits set > in all the bulk URBs where QEMU currently has them clear. > --- > hw/usb/dev-serial.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c > index ef33bcd127..5389235f17 100644 > --- a/hw/usb/dev-serial.c > +++ b/hw/usb/dev-serial.c > @@ -332,7 +332,7 @@ static void usb_serial_handle_control(USBDevice *dev, > USBPacket *p, > break; > case DeviceInVendor | FTDI_GET_MDM_ST: > data[0] = usb_get_modem_lines(s) | 1; > - data[1] = 0; > + data[1] = FTDI_THRE | FTDI_TEMT; > p->actual_length = 2; > break; > case DeviceOutVendor | FTDI_SET_EVENT_CHR: > -- > 2.24.1 > -- Samuel c> ah (on trouve fluide glacial sur le net, ou il faut aller dans le monde reel ?) s> dans le monde reel c> zut
