Subject: Re: ath10k and min_gcd + adhoc issues in 4.20 kernel
From:   Ben Greear <greearb@candelatech.com>
To:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
References: <3dfff3d9-a070-f3a3-723c-d1442ec06bc5@candelatech.com>
Organization: Candela Technologies
Message-ID: <5475c4c5-e30d-f254-e3b8-43b52b83a198@candelatech.com>
Date:   Thu, 4 Apr 2019 13:45:16 -0700
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Hello,

Any comments on this below?

Thanks,
Ben

On 1/15/19 3:29 PM, Ben Greear wrote:
> I just updated to 4.20 and ported forward my ath10k patches.  Now the driver
> will not register with mac80211 because this warning hits in net/wireless/core.c:
> 
>              /*
>               * This isn't well-defined right now. If you have an
>               * IBSS interface, then its beacon interval may change
>               * by joining other networks, and nothing prevents it
>               * from doing that.
>               * So technically we probably shouldn't even allow AP
>               * and IBSS in the same interface, but it seems that
>               * some drivers support that, possibly only with fixed
>               * beacon intervals for IBSS.
>               */
>              if (WARN_ON(types & BIT(NL80211_IFTYPE_ADHOC) &&
>                      c->beacon_int_min_gcd)) {
>                  return -EINVAL;
>              }
> 
> 
> It looks like this was triggered by:
> 
> Commit 0c317a02ca982ca093e71bf07cb562265ba40032
> Author: Purushottam Kushwaha <pkushwah@qti.qualcomm.com>
> Date:   Wed Oct 12 18:26:51 2016 +0530
> 
>      cfg80211: support virtual interfaces with different beacon intervals
> 
> and
> 
> commit 8ebee73b574ad3dd1f14d461f65ceaffbd637650
> Author: Anilkumar Kolli <akolli@codeaurora.org>
> Date:   Wed Mar 28 12:19:40 2018 +0300
> 
>      ath10k: advertize beacon_int_min_gcd
> 
> 
> To be honest, I don't see why that check for beacon_int_min_gcd is in the registration
> logic.  Having it be '1' means that the driver/nic/firmware is flexible on pretty much
> any combination of beacon interval, so why should that trigger the WARN_ON case?
> 
> Thanks,
> Ben
> 


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com