Re: ath10k: antenna bitmask support?

[Brian Norris <briannorris@chromium.org>]

Hi Ben,

On Tue, Aug 07, 2018 at 06:19:22AM -0700, Ben Greear wrote:
> On 08/06/2018 07:08 PM, Brian Norris wrote:
> > Hi all,
> > 
> > I'm looking at ancient changes like this:
> > 
> > commit 5572a95b4b5768187652a346356e39e7542ca6e0
> > Author: Ben Greear <greearb@candelatech.com>
> > Date:   Mon Nov 24 16:22:10 2014 +0200
> > 
> >     ath10k: apply chainmask settings to vdev on creation
> > 
> > since I see that some firmwares seem to crash a lot if you apply certain
> > chainmask settings (e.g., 0x2).
> > 
> > Is it really expected that you can set gaps in the chainmask or not? I
> > ask because I've been trying to use this for doing some antenna
> > configuration verification (e.g., disable all but one antenna and see
> > what happens), and this works as expected on APs I have running IPQ8064
> > (QCA988X?), but it crashes the firmware on IPQ4019.
> 
> I don't think you can even directly set the chainmask in the firmware,

Well, I guess the WMI interface is a bit strange then: it appears to
take a raw mask -- e.g.:

        ret = ath10k_wmi_pdev_set_param(ar, ar->wmi.pdev_param->tx_chain_mask,
                                        tx_ant);

but I guess that doesn't mean it *really* accepts a mask? You have to
presuppose what values it will accept?

> and from my previous looking at the firmware, it is not designed to support
> gaps.

OK, thanks for the info.

> If you want to determine if an antenna is working, you can look at the per-chain
> RSSI stats when receiving frames using all available antenna (ie, 3x3 rates for a 3x3 NIC).

That's not quite the same as verifying each antenna separately, but it
might be good enough. I suppose this wasn't really considered when some
of the test frameworks I'm using were written, seeing as per-chain
signal reports weren't even available in ath10k until relatively
recently:

commit 8241253d03fe9098e98315a4d66027ae31ab65c5
Author: Norik Dzhandzhapanyan <norikd@gmail.com>
Date:   Mon Jun 12 18:03:34 2017 +0300

    ath10k: add per chain RSSI reporting

Thanks,
Brian

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