[ath9k-devel] ath9k: debug messaging

[ath9k-devel] ath9k: debug messaging

[mike b]

Hello Almighty C Wizards and Ath9k Maintainers!

Since couple of days I have been seeing some odd log messages in the krb
returned by the ath9k module. Those messages look like the following:

4502.875550] ath: phy0: Failed to stop TX DMA, queues=0x002!
[ 4502.889646] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000028
AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 4502.889688] ath: phy0: Could not stop RX, we could be confusing the DMA
engine when we start RX up

As I am not fluent in C, it's a painful process for me to traverse through
the source code to look up this stuff, thus I would appreciate some
feedback on what's going on with my wlan controller.

I have managed to narrow it down to:

static bool ath_beacon_dtim_pending_cab(struct sk_buff *skb)

defined in recv.c.

By reading this part:

 if (!(ah->ah_flags & AH_UNPLUGGED) &&
            unlikely(!stopped)) {
                ath_err(ath9k_hw_common(sc->sc_ah),
                        "Could not stop RX, we could be "
                        "confusing the DMA engine when we start RX up\n");
                ATH_DBG_WARN_ON_ONCE(!stopped);
        }
and reviewing some of the header files I would translate it to: 'if
ah_flags does not include AH_UNPLUGGED (macro for 0x2, physically removed
device) and we didn't stop (stop what?), report a bit unclear error'. :D

So I get that this controller accesses DMA zone instead of going through
the CPU to do something (something with queuing packets, beacon?) but it's
beyond me to fully understand it (wish I could, really!). Also, I guess
that those macros returned in the log are controllers registers (reg.h),
something was written to it, but those values also tell me nothing.

Any hints would be appreciated! Kernel's config attached, as well as s
debugfs snapshot, maybe that will be of any use to you. :) According to
signature under sysfs, the controller itself should be Atheros AR9485.

P.S can't get version of the actual driver anywhere, sorry! But if there's
anything else needed, just let me know!

Thanks!

Regards,
Michal
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