From: James Prestwood <prestwoj@gmail.com>
To: Denis Kenzior <denkenz@gmail.com>,
Alagu Sankar <alagusankar@gmail.com>,
iwd@lists.linux.dev
Subject: Re: 40MHz Bandwidth in AP mode
Date: Mon, 13 Mar 2023 09:56:11 -0700 [thread overview]
Message-ID: <e9d64559432a759066a00fa1d4bd753c517f8cd4.camel@gmail.com> (raw)
In-Reply-To: <00c6a4a6-425d-aede-1e09-b85a56df081a@gmail.com>
On Mon, 2023-03-13 at 10:29 -0500, Denis Kenzior wrote:
> Hi Alagu,
>
> On 3/13/23 05:07, Alagu Sankar wrote:
> > Hi,
> >
> > We are testing the iwd-2.3 version in AP mode for one of our
> > requirements. When trying to configure the AP mode in Channel 36, it
> > was always selecting 20MHz. The band_freq_to_ht_chandef() function
> > is
> > supposed to select the best bandwidth. As we see, channel 36 is
> > configured as 40Mhz capable (operating_class 116). Debugging this
> > further, we see that 40MHz spacing is rejected due to the following
> > condition
> > if (info->flags & PRIMARY_CHANNEL_UPPER && attr->no_ht40_plus)
> > continue;
> > if (info->flags & PRIMARY_CHANNEL_LOWER && attr->no_ht40_minus)
> > continue;
> > Channel 36 is configured as PRIMARY_CHANNEL_LOWER and the NL80211
> > attribute is indicating no_ht40_minus for this, but as per the
>
> So if NL80211 reports no_ht40_minus, we can't use this channel for
> 40HT:
>
> * @NL80211_FREQUENCY_ATTR_NO_HT40_MINUS: HT40- isn't possible with this
> * channel as the control channel
>
> > condition above, this is skipped. The check above seems incorrect.
>
> Why do you say that?
>
> Is the currently set regdom somehow restricting HT40 operation? Does
> setting
> the regdom country help? Perhaps via [General].Country? See man 5
> iwd.config.
>
> > Can you please let me know if 40MHz bandwidth is tested on AP mode?
> >
>
> Yes, but things can always be tested better. Our AP support is still
> quite
> experimental.
Yes, AP mode certainly could use more testing but the adapters I have
tested on have worked with 40MHz.
As Denis said just because the operating class allows 40Mhz doesn't
mean your wifi hardware or country allow that operation.
To tell 100% in your case you'd need to get an iwmon log of IWD
starting up. This will get a full log of any channel restrictions, more
info here: https://iwd.wiki.kernel.org/debugging
Thanks,
James
>
> Regards,
> -Denis
>
next prev parent reply other threads:[~2023-03-13 16:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAH4auOnuK_dDemZRF4BMq3LPL6A5cmLfSgJKeFVKAYZUNGAk2w@mail.gmail.com>
2023-03-13 10:07 ` 40MHz Bandwidth in AP mode Alagu Sankar
2023-03-13 15:29 ` Denis Kenzior
2023-03-13 16:56 ` James Prestwood [this message]
2023-03-14 6:14 ` Alagu Sankar
2023-03-14 15:24 ` James Prestwood
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