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dev-serial: add always-plugged property to ensure USB device is always attached

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Some operating systems will generate a new device ID when a USB device is unplugged
and then replugged into the USB. If this is done whilst switching between multiple
applications over a virtual serial port, the change of device ID requires going
back into the OS/application to locate the new device accordingly.

Add a new always-plugged property that if specified will ensure that the device
always remains attached to the USB regardless of the state of the backend
chardev.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-id: 20201027150456.24606-7-mark.cave-ayland@ilande.co.uk
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Mark Cave-Ayland 2020-10-27 15:04:54 +00:00 committed by Gerd Hoffmann
parent 687dfe63e3
commit 66007a9567
1 changed files with 6 additions and 3 deletions
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9
hw/usb/dev-serial.c
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@ -97,6 +97,7 @@ struct USBSerialState {
uint8_t event_chr;
uint8_t error_chr;
uint8_t event_trigger;
bool always_plugged;
QEMUSerialSetParams params;
int latency; /* ms */
CharBackend cs;
@ -516,12 +517,12 @@ static void usb_serial_event(void *opaque, QEMUChrEvent event)
s->event_trigger |= FTDI_BI;
break;
case CHR_EVENT_OPENED:
if (!s->dev.attached) {
if (!s->always_plugged && !s->dev.attached) {
usb_device_attach(&s->dev, &error_abort);
}
break;
case CHR_EVENT_CLOSED:
if (s->dev.attached) {
if (!s->always_plugged && s->dev.attached) {
usb_device_detach(&s->dev);
}
break;
@ -556,7 +557,8 @@ static void usb_serial_realize(USBDevice *dev, Error **errp)
usb_serial_event, NULL, s, NULL, true);
usb_serial_handle_reset(dev);
if (qemu_chr_fe_backend_open(&s->cs) && !dev->attached) {
if ((s->always_plugged || qemu_chr_fe_backend_open(&s->cs)) &&
!dev->attached) {
usb_device_attach(dev, &error_abort);
}
s->intr = usb_ep_get(dev, USB_TOKEN_IN, 1);
@ -584,6 +586,7 @@ static const VMStateDescription vmstate_usb_serial = {
static Property serial_properties[] = {
DEFINE_PROP_CHR("chardev", USBSerialState, cs),
DEFINE_PROP_BOOL("always-plugged", USBSerialState, always_plugged, false),
DEFINE_PROP_END_OF_LIST(),
};