usb-serial: Fix timeout closing the device
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 <jandryuk@gmail.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Message-id: 20200316174610.115820-5-jandryuk@gmail.com Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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@ -332,7 +332,7 @@ static void usb_serial_handle_control(USBDevice *dev, USBPacket *p,
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break;
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break;
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case DeviceInVendor | FTDI_GET_MDM_ST:
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case DeviceInVendor | FTDI_GET_MDM_ST:
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data[0] = usb_get_modem_lines(s) | 1;
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data[0] = usb_get_modem_lines(s) | 1;
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data[1] = 0;
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data[1] = FTDI_THRE | FTDI_TEMT;
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p->actual_length = 2;
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p->actual_length = 2;
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break;
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break;
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case DeviceOutVendor | FTDI_SET_EVENT_CHR:
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case DeviceOutVendor | FTDI_SET_EVENT_CHR:
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