On Tue, 30 May 2023, John Nielsen wrote:
I’m trying to wrap my head around the code in sys/dev/ath/ath_hal , partly for
my own edification but mostly due to wanting to fix this bug:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255337
The card in question is an AR9462, branded (I think) as a Dell Wireless 1901
with this ID:
vendor=0x168c device=0x0034 subvendor=0x1028 subdevice=0x020d
The card is identified and appears to initialize correctly but it has a
default/bogus MAC address of 00:02:03:04:05:06 and is never able to scan any
networks. It does work fine under Linux, so I’m attempting to compare the two
codebases. But since I’m not a device developer and haven’t done much C since
my undergraduate work, I’m having a bit of trouble.
I’m open to any pointers but I’d specifically like to work out the following
(unless I’m way off base, in which case I’d like to know that too):
1) Where does the default MAC address come from? In the Linux driver it looks
like it’s here:
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/tree/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c#n49
I don’t see any such definition in the FreeBSD code.
No idea, but you should end up in a call to ar9300_get_mac_address()
from sys/contrib/dev/ath/ath_hal/ar9300/ar9300_misc.c if my guess is right.
The call comes from sys/dev/ath/if_ath.c ath_hal_getmac().
Hope that helps you to trace this.
2) When ath_hal_attach() calls chip->attach(), which code is actually called
(and how/where is that determined)?
3) Is there any equivalent in the FreeBSD code for this Linux process of trying
to read the EEPROM from multiple different addresses? (Is it necessary?)
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/tree/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c#n3299
See also:
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/drivers/net/wireless/ath/ath9k?id=528782ecf59f7bab2f1368628a479f49be59b512
and the definitions here:
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/tree/drivers/net/wireless/ath/ath9k/ar9003_eeprom.h#n78
(I don’t see any of those BASE_ADDR values referenced or defined anywhere in
FreeBSD)
4) In general, what code should I be looking at to see how the EEPROM is read
and interpreted for a specific card?
Any help appreciated!
Thanks,
JN
--
Bjoern A. Zeeb r15:7
