Also implement the behaviour reported in Linux's ftdi_sio.c whereby if an
invalid
data_bits value is provided then the hardware defaults to using 8.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk>
---
hw/usb/dev-serial.c | 17 +++++++++++++++++
hw/usb/trace-events | 1 +
2 files changed, 18 insertions(+)
diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
index 919e25e1d9..4c374d0790 100644
--- a/hw/usb/dev-serial.c
+++ b/hw/usb/dev-serial.c
@@ -308,6 +308,23 @@ static void usb_serial_handle_control(USBDevice *dev,
USBPacket *p,
break;
}
case VendorDeviceOutRequest | FTDI_SET_DATA:
+ switch (value & 0xff) {
+ case 7:
+ s->params.data_bits = 7;
+ break;
+ case 8:
+ s->params.data_bits = 8;
+ break;
+ default:
+ /*
+ * According to a comment in Linux's ftdi_sio.c original FTDI
+ * chips fall back to 8 data bits for unsupported data_bits
+ */
+ trace_usb_serial_unsupported_data_bits(bus->busnr, dev->addr,
+ value & 0xff);
+ s->params.data_bits = 8;
+ }
+
switch (value & FTDI_PARITY) {
case 0:
s->params.parity = 'N';
diff --git a/hw/usb/trace-events b/hw/usb/trace-events
index 9e984b2e0c..0d0a3e5f2a 100644
--- a/hw/usb/trace-events
+++ b/hw/usb/trace-events
@@ -327,6 +327,7 @@ usb_serial_handle_control(int bus, int addr, int request,
int value) "dev %d:%d
usb_serial_unsupported_parity(int bus, int addr, int value) "dev %d:%d
unsupported parity %d"
usb_serial_unsupported_stopbits(int bus, int addr, int value) "dev %d:%d
unsupported stop bits %d"
usb_serial_unsupported_control(int bus, int addr, int request, int value) "dev
%d:%d got unsupported/bogus control 0x%x, value 0x%x"
+usb_serial_unsupported_data_bits(int bus, int addr, int value) "dev %d:%d
unsupported data bits %d, falling back to 8"
usb_serial_bad_token(int bus, int addr) "dev %d:%d bad token"
usb_serial_set_baud(int bus, int addr, int baud) "dev %d:%d baud rate %d"
usb_serial_set_data(int bus, int addr, int parity, int data, int stop) "dev
%d:%d parity %c, data bits %d, stop bits %d"
--
2.20.1
