Hi Sebastian,
On Mon, Aug 6, 2018 at 9:11 PM Sebastian Gottschall
<[email protected]> wrote:
>
> Am 07.08.2018 um 04:08 schrieb Brian Norris:
...
> > 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.
...
> from what i know, gaps will not work. so valid masks are only like 0x1,
> 0x3, 0x7, 0xf. so same behaviour as for ath9k
Thanks for your response. The thing is, masks like 0x2 and 0x4 *do*
appear to work for IPQ8064, as I noted above. Let me elaborate.
I tested with a conductively-wired setup, where antennas are wired
directly from an AP to a client (with reasonable attenuation), only 2
of the 3 AP antennas are connected, and the client supports reporting
signal strength on a per-antenna basis. If I set the AP's mask to 0x1,
I see strong signal only on the client's antenna 1; if set to 0x2, I
see strong signal only on the client's antenna 2; and if I set it to
0x4, I see only a very weak signal (presumably over the air, even
without any antenna).
In other words, I think this clearly works for some chipsets. I just
wonder if anybody knows anything about why it does or doesn't work on
a give chipset.
I also acknowledge that while the firmware may work properly, ath10k
may not always account for this properly (hence, proposals like the
diff in the previous email). I see several occasions where ath10k does
a simple integer greater/less-than comparison between 1 and
cfg_{tx,rx}_chainmask, which seems wrong. But my question is more
geared toward firmware and hardware support; fixing drivers is
relatively easy ;)
Regards,
Brian
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