2019-07-02 12:43:29

by Jes Sorensen

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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 <[email protected]> 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 <[email protected]>
>
> 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


2019-07-03 07:42:39

by Daniel Drake

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Subject: Re: [PATCH] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

On Tue, Jul 2, 2019 at 8:42 PM Jes Sorensen <[email protected]> wrote:
> 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.

Yeah, I didn't mean bring over quite so literally.. Chris is studying
it and figuring out the neatest way to reimplement the required bits.

As for the relationship with bluetooth.. actually the bug that Chris
is working on here is that the rtl8xxxu wifi signal is totally
unusable *until* the bluetooth driver is loaded.
Once the bluetooth driver is loaded, at the point of bluetooth
firmware upload, the rtl8xxxu signal magiaclly strength becomes good.
I think this is consistent with other rtl8xxxu problem reports that we
saw lying around, although they had not been diagnosed in so much
detail.
The rtl8723bu vendor driver does not suffer this problem, it works
fine with or without the bluetooth driver in place.

Daniel

2019-07-03 13:00:43

by Jes Sorensen

[permalink] [raw]
Subject: Re: [PATCH] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

On 7/3/19 3:42 AM, Daniel Drake wrote:
> On Tue, Jul 2, 2019 at 8:42 PM Jes Sorensen <[email protected]> wrote:
>> 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.
>
> Yeah, I didn't mean bring over quite so literally.. Chris is studying
> it and figuring out the neatest way to reimplement the required bits.
>
> As for the relationship with bluetooth.. actually the bug that Chris
> is working on here is that the rtl8xxxu wifi signal is totally
> unusable *until* the bluetooth driver is loaded.

So this is not my experience at all from when I wrote the code. The
8723bu dongle I used for it came up just fine.

> Once the bluetooth driver is loaded, at the point of bluetooth
> firmware upload, the rtl8xxxu signal magiaclly strength becomes good.
> I think this is consistent with other rtl8xxxu problem reports that we
> saw lying around, although they had not been diagnosed in so much
> detail.

See this is the very opposite of what I have experienced. The bluetooth
driver ruins the signal when it's loaded with my dongle.

> The rtl8723bu vendor driver does not suffer this problem, it works
> fine with or without the bluetooth driver in place.

My point is this seems to be very dongle dependent :( We have to be
careful not breaking it for some users while fixing it for others.

Cheers,
Jes