linux-kernel - Re: [PATCH] ath9k: turn on btcoex

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Message-ID: <CAKR_QV+6yW6c51ve3sV=yadhL5fgPDTKQOfahnjNhtE1RHDzUw@mail.gmail.com>
Date:   Thu, 23 Aug 2018 19:06:04 +0200
From:   Tom Psyborg <pozega.tomislav@...il.com>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Felix Fietkau <nbd@....name>, ath9k-devel@....qualcomm.com,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ath9k: turn on btcoex_enable as default

I keep this setting on all the time and just when i read this mail
again i'm suspicious if the bluetooth could actually have an impact on
wifi reception? I am using AR9462 card and it can transmit at 215Mbps
average, but receives only about 125Mbps (2spatial streams AP, 2.4GHz,
AR9531)

On 23/08/2018, Kalle Valo <kvalo@...eaurora.org> wrote:
> Kai-Heng Feng <kai.heng.feng@...onical.com> writes:
>
>> at 12:15, Kai Heng Feng <kai.heng.feng@...onical.com> wrote:
>>
>>>
>>>
>>>> On 10 Feb 2018, at 10:05 PM, Felix Fietkau <nbd@....name> wrote:
>>>>
>>>> On 2018-02-10 14:56, Kai Heng Feng wrote:
>>>>>> On 9 Feb 2018, at 3:16 PM, Kalle Valo <kvalo@...eaurora.org> wrote:
>>>>>> Sure, but we have to make sure that we don't create regressions on
>>>>>> existing systems. For example, did you test this with any system
>>>>>> which
>>>>>> don't support btcoex? (just asking, haven't tested this myself)
>>>>>
>>>>> No not really, but I will definitely test it.
>>>>> The only module I have that uses ath9k is Dell’s DW1707.
>>>>> How do I check if it support btcoex or not?
>>>> I just reviewed the code again, and I am sure that we cannot merge this
>>>> patch. Enabling the btcoex parameter makes the driver enable a whole
>>>> bunch of code starting timers, listening to some GPIOs, etc.
>>>>
>>>> On non-btcoex systems, some of those GPIOs might be floating or even
>>>> connected to different things, which could cause a lot of undefined
>>>> behavior.
>>>>
>>>> This is simply too big a risk, so there absolutely needs to be a
>>>> whitelist for systems that need this, otherwise it has to remain
>>>> disabled by default.
>>>
>>> So what information can we use to whitelist btcoex chips?
>>> Can we get btcoex support status at ath9k probing?
>>
>> Sorry for bringing this up again.
>>
>> Is DMI based match an acceptable approach for ath9k?
>
> I don't know what Felix thinkgs, but to me using DMI sounds like a good
> idea to try, assuming the matches are unique enough and there's no risk
> of enabling bt coex on wrong platforms. Should the PCI bus number etc
> checked as well in case the user adds more ath9k devices to the
> platform?
>
> But of course I need to see the patch to comment more.
>
> --
> Kalle Valo
>