Defaults cxadc3-linux/cxadc.c file to have the defaults you like. at stock, it will look like this:
static int latency = -1; (leave this alone)
static int audsel = -1;
static int vmux = 2;
static int level = 16;
static int tenbit;
static int tenxfsc;
static int sixdb = 1;
static int crystal = 28636363;
But you could change it to:
static int latency = -1; (leave this alone)
static int audsel = -1;
static int vmux = 1;
static int level = 0;
static int tenbit = 1;
static int tenxfsc = 1;
static int sixdb = 0;
static int crystal = 40000000;
Then redo the make and sudo make modules_install commands. Then next reboot, it will come up with those settings as the default.
This can be done with the pcimem tool. Get it from here:
https://github.com/billfarrow/pcimem
Build it with make. To use, consult lspci for the PCI address of
your card. This will be different depending on motherboard and slot.
Example output:
03:00.0 Multimedia video controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder (rev 05)
03:00.4 Multimedia controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder [IR Port] (rev 05)
Here we want the video controller at address 03:00.0 - not the
IR port. Next you need to find that device in sysfs. Due to topology
it can be nested under other devices. The quickest way to find it:
find /sys/devices -iname '*03:00.0'
Output:
/sys/devices/pci0000:00/0000:00:1c.5/0000:02:00.0/0000:03:00.0
To use pcimem we take that filename and add "/resource0" to the end. Then to read a register we do this:
./pcimem /sys/devices/pci0000:00/0000:00:1c.5/0000:02:00.0/0000:03:00.0/resource0 0x2f0000
0x2f0000 is the device ID register and it should begin with 0x88. Output:
0x2F0000: 0x880014F1
To write to a register, specify a value after the address.