Hello,
(Cc-ing Aurelien who introduced the support for modem control, and Jason
who added the missing THRE and TEMT flags).
Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +0000, a ecrit:
The FTDI_GET_MDM_ST response should only return a single byte indicating the
modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h header
file).
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
hw/usb/dev-serial.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
index 4c374d0790..fa734bcf54 100644
--- a/hw/usb/dev-serial.c
+++ b/hw/usb/dev-serial.c
@@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice *dev,
USBPacket *p,
/* TODO: TX ON/OFF */
break;
case VendorDeviceRequest | FTDI_GET_MDM_ST:
- data[0] = usb_get_modem_lines(s) | 1;
- data[1] = FTDI_THRE | FTDI_TEMT;
- p->actual_length = 2;
+ data[0] = usb_get_modem_lines(s);
+ p->actual_length = 1;
Err, but Linux' drivers/usb/serial/ftdi_sio.c:ftdi_process_packet()
contradicts this:
if (len < 2) {
dev_dbg(&port->dev, "malformed packet\n");
return 0;
}
status = buf[0] & FTDI_STATUS_B0_MASK;
if (status != priv->prev_status) {
char diff_status = status ^ priv->prev_status;
if (diff_status & FTDI_RS0_CTS)
port->icount.cts++;
[...]
/* save if the transmitter is empty or not */
if (buf[1] & FTDI_RS_TEMT)
priv->transmit_empty = 1;
else
priv->transmit_empty = 0;
Did you actually get an issue with seeing this packet contain two bytes?