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Subject: Re: [PATCH] ath9k: turn on btcoex_enable as default
From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <6A0F65EF-A7C4-469F-8FAF-CBE314676237@canonical.com>
Date:   Thu, 23 Aug 2018 09:33:56 +0800
Cc:     Kalle Valo <kvalo@codeaurora.org>, ath9k-devel@qca.qualcomm.com,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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To:     Felix Fietkau <nbd@nbd.name>
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at 12:15, Kai Heng Feng <kai.heng.feng@canonical.com> wrote:

>
>
>> On 10 Feb 2018, at 10:05 PM, Felix Fietkau <nbd@nbd.name> wrote:
>>
>> On 2018-02-10 14:56, Kai Heng Feng wrote:
>>>> On 9 Feb 2018, at 3:16 PM, Kalle Valo <kvalo@codeaurora.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?

Kai-Heng

>
> Kai-Heng
>
>> - Felix