Why: FTDI USB serial speed issue with SCS P4 Dragon short-wave modems,
a custom baud-rate is required
Solution: set special baud-rate by setting a custom divisor on 38400B
Signed-off-by: Robert Wolters <robert@xxxxxxxxxxxxxxxxx>
--- ftdi_sio.c 2021-04-21 13:01:00.000000000 +0200
+++ ftdi_sio.c 2021-04-26 18:53:00.819175707 +0200
@@ -97,6 +97,7 @@
static int ftdi_8u2232c_probe(struct usb_serial *serial);
static void ftdi_USB_UIRT_setup(struct ftdi_private *priv);
static void ftdi_HE_TIRA1_setup(struct ftdi_private *priv);
+static void ftdi_SCS_DR7X00_setup(struct ftdi_private *priv);
static const struct ftdi_sio_quirk ftdi_jtag_quirk = {
.probe = ftdi_jtag_probe,
@@ -122,6 +123,10 @@
.probe = ftdi_8u2232c_probe,
};
+static const struct ftdi_sio_quirk ftdi_SCS_DR7X00_quirk = {
+ .port_probe = ftdi_SCS_DR7X00_setup,
+};
+
/*
* The 8U232AM has the same API as the sio except for:
* - it can support MUCH higher baudrates; up to:
@@ -157,8 +162,12 @@
{ USB_DEVICE(FTDI_VID, FTDI_EV3CON_PID) },
{ USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_0_PID) },
{ USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_1_PID) },
- { USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_2_PID) },
- { USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_3_PID) },
+ { USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_2_PID) ,
+ .driver_info = (kernel_ulong_t)&ftdi_SCS_DR7X00_quirk },
+ { USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_3_PID) ,
+ .driver_info = (kernel_ulong_t)&ftdi_SCS_DR7X00_quirk },
{ USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_4_PID) },
{ USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_5_PID) },
{ USB_DEVICE(FTDI_VID, FTDI_SCS_DEVICE_6_PID) },
@@ -2296,6 +2305,15 @@
priv->force_rtscts = 1;
}
+/* Setup for the SCS P4dragon DR-7X00 devices, which require
+ *hardwired baud-rate of 829440 (38400 gets mapped to 829440) */
+static void ftdi_SCS_DR7X00_setup(struct ftdi_private *priv)
+{
+ priv->flags |= ASYNC_SPD_CUST;
+ priv->custom_divisor = 29;
+ priv->force_baud = 38400;
+}
+
/*
* Module parameter to control latency timer for NDI FTDI-based USB devices.
* If this value is not set in /etc/modprobe.d/ its value will be set
