linux-kernel - Re: [PATCH] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

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Date:   Tue, 2 Jul 2019 08:42:19 -0400
From:   Jes Sorensen <jes.sorensen@...il.com>
To:     Daniel Drake <drake@...lessm.com>, Chris Chiu <chiu@...lessm.com>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        David Miller <davem@...emloft.net>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Linux Upstreaming Team <linux@...lessm.com>,
        Larry Finger <Larry.Finger@...inger.net>
Subject: Re: [PATCH] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

On 7/1/19 4:27 AM, Daniel Drake wrote:
> Hi Chris,
> 
> On Thu, Jun 27, 2019 at 5:53 PM Chris Chiu <chiu@...lessm.com> wrote:
>> The WiFi tx power of RTL8723BU is extremely low after booting. So
>> the WiFi scan gives very limited AP list and it always fails to
>> connect to the selected AP. This module only supports 1x1 antenna
>> and the antenna is switched to bluetooth due to some incorrect
>> register settings.
>>
>> This commit hand over the antenna control to PTA, the wifi signal
>> will be back to normal and the bluetooth scan can also work at the
>> same time. However, the btcoexist still needs to be handled under
>> different circumstances. If there's a BT connection established,
>> the wifi still fails to connect until disconneting the BT.
>>
>> Signed-off-by: Chris Chiu <chiu@...lessm.com>
> 
> Really nice work finding this!
> 
> I know that after this change, you plan to bring over the btcoexist
> code from the vendor driver (or at least the minimum required code)
> for a more complete fix, but I'm curious how you found these magic
> register values and how they compare to the values used by the vendor
> driver with btcoexist?

We definitely don't want to bring over the vendor code, since it's a
pile of spaghetti, but we probably need to get something sorted. This
went down the drain when the bluetooth driver was added without taking
it into account - long after this driver was merged.

Cheers,
Jes