On 26/10/2020 13:00, Jason Andryuk wrote:
On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault <samuel.thiba...@gnu.org> wrote:
Mark Cave-Ayland, le lun. 26 oct. 2020 10:58:43 +0000, a ecrit:
On 26/10/2020 09:54, Samuel Thibault wrote:
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-ayl...@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;
[...]
A quick test shows my Chipi-X returns 0x1 0x60 with nothing attached in
response to FTDI_SIO_GET_MODEM_STATUS_REQUEST: assuming the reply length
should be 2 bytes, the comment about B0-B3 being zero and the response from
my Chip-X above suggests that the "| 1" should still be dropped from the
response.
Aurelien, you introduced the "| 1" in
commit abb8a13918ecc1e8160aa78582de9d5224ea70df
Author: Aurelien Jarno <aurel...@aurel32.net>
Date: Wed Aug 13 04:23:17 2008 +0000
usb-serial: add support for modem lines
[...]
@@ -357,9 +393,9 @@ static int usb_serial_handle_control(USBDevice *dev, int
request, int value,
/* TODO: TX ON/OFF */
break;
case DeviceInVendor | FTDI_GET_MDM_ST:
- /* TODO: return modem status */
- data[0] = 0;
- ret = 1;
+ data[0] = usb_get_modem_lines(s) | 1;
+ data[1] = 0;
+ ret = 2;
break;
do you know exactly what it is for?
Hi,
I'm not particularly familiar with the FTDI USB serial devices. I
found setting FTDI_THRE | FTDI_TEMT by comparing with real hardware.
A little searching found this:
https://elixir.bootlin.com/linux/latest/source/drivers/usb/serial/ftdi_sio.h#L541
That shows "B0 Reserved - must be 1", so maybe that is why "| 1" was added?
Right - that's for the modem status returned as part of the first 2 status bytes for
incoming data which is slightly different from modem status returned directly from
FTDI_SIO_GET_MODEM_STATUS:
https://elixir.bootlin.com/linux/latest/source/drivers/usb/serial/ftdi_sio.h#L423.
It is the latter which this patch changes and appears to match what I see on my
Chipi-X hardware here.
ATB,
Mark.
