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From:   Tony Chuang <yhchuang@realtek.com>
To:     Kalle Valo <kvalo@codeaurora.org>
CC:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        "briannorris@chromium.org" <briannorris@chromium.org>,
        Arend Van Spriel <arend.vanspriel@broadcom.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        "tamizhr@codeaurora.org" <tamizhr@codeaurora.org>
Subject: RE: [PATCH v2 2/2] rtw88: add a debugfs entry to enable/disable coex mechanism
Thread-Topic: [PATCH v2 2/2] rtw88: add a debugfs entry to enable/disable coex
 mechanism
Thread-Index: AQHV9eid5DTKsHzIFkaU/75iZgvikahFzUJQ
Date:   Fri, 13 Mar 2020 02:23:38 +0000
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References: <20200309075852.11454-1-yhchuang@realtek.com>
        <20200309075852.11454-3-yhchuang@realtek.com>
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Kalle Valo <kvalo@codeaurora.org> :

> <yhchuang@realtek.com> writes:
> 
> > From: Yan-Hsuan Chuang <yhchuang@realtek.com>
> >
> > Sometimes we need to stop the coex mechanism to debug, so that we
> > can manually control the device through various outer commands.
> > Hence, add a new debugfs coex_enable to allow us to enable/disable
> > the coex mechanism when driver is running.
> >
> > To disable coex
> > echo 0 > /sys/kernel/debug/ieee80211/phyX/rtw88/coex_enable
> >
> > To enable coex
> > echo 1 > /sys/kernel/debug/ieee80211/phyX/rtw88/coex_enable
> >
> > To check coex dm is enabled or not
> > cat /sys/kernel/debug/ieee80211/phyX/rtw88/coex_enable
> 
> I forgot, did we add a command to nl80211 for managing btcoex? At least
> we have talking about that for years. Please check that first before
> adding a debugfs interface for this.
> 

Yes, I found there was a thread [1] talking about adding a callback to
enable/disable btcoex, but it seems not get applied eventually.

And there's another thread [2] talking about add a btcoex subsystem.
But seems like nobody can implement it cleanly in the host.

I think adding btcoex subsystem could have a lot of pain since each
vendor is using different mechanism controlling the btcoex, and it
usually comes with RF related design which is difficult to write a common
function to deal with all kinds of them.

Yen-Hsuan

[1] https://patchwork.kernel.org/patch/10252135/
[2] https://www.spinics.net/lists/linux-wireless/msg133333.html