We are using the WL1837MOD module from TI connected to an iMX7D.
After upgrading from Linux 4.9.67 to 5.4.3, the WLAN function is still working but not the BT part.
We are using this command to start and set up the BT part:
hciattach -p /dev/ttymxc2 texas
I have assigned the UART signals to a logic analyzer and can confirm they are operating exactly the same way as for the 4.9.67 kernel. Hence I suspec it is the TTY stack that for some reason does not provide the data coming rom the UART interface to the WL1837 module.
I have made some debugging in the source code for hciattach; and found that not a single byte is read out of /dev/ttymxc2.
I put a break in the first read call - it will never return. It is in hciattach.c in the yellow line below:
int read_hci_event(int fd, unsigned char* buf, int size)
{
int remain, r;
int count = 0;
if (size <= 0)
return -1;
/* The first byte identifies the packet type. For HCI event packets, it
* should be 0x04, so we read until we get to the 0x04. */
while (1) {
r = read(fd, buf, 1);
The reason for upgrading Linux is for an upcoming release using WoWlan. This issue is the main and only blocking factor now.
Please guide me to how to precede debugging to resolve this issue.
Thanks,
Trond
