netdev - Re: [PATCH] wifi: rtl8xxxu: fixing transmisison failure for rtl8192eu

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Date:   Wed, 21 Dec 2022 14:14:21 +0200
From:   Bitterblue Smith <rtl8821cerfe2@...il.com>
To:     Ping-Ke Shih <pkshih@...ltek.com>,
        "Jes.Sorensen@...il.com" <Jes.Sorensen@...il.com>,
        "JunASAKA@...040330.moe" <JunASAKA@...040330.moe>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "kvalo@...nel.org" <kvalo@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "pabeni@...hat.com" <pabeni@...hat.com>
Subject: Re: [PATCH] wifi: rtl8xxxu: fixing transmisison failure for rtl8192eu

On 21/12/2022 03:42, Ping-Ke Shih wrote:
> On Tue, 2022-12-20 at 15:03 +0200, Bitterblue Smith wrote:
>> On 20/12/2022 07:44, Ping-Ke Shih wrote:
>>>
>>>> -----Original Message-----
>>>> From: Jun ASAKA <JunASAKA@...040330.moe>
>>>> Sent: Saturday, December 17, 2022 11:07 AM
>>>> To: Jes.Sorensen@...il.com
>>>> Cc: kvalo@...nel.org; davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org; 
>>>> pabeni@...hat.com;
>>>> linux-wireless@...r.kernel.org; netdev@...r.kernel.org; linux-kernel@...r.kernel.org; Jun
>>>> ASAKA
>>>> <JunASAKA@...040330.moe>
>>>> Subject: [PATCH] wifi: rtl8xxxu: fixing transmisison failure for rtl8192eu
>>>>
>>>> Fixing transmission failure which results in
>>>> "authentication with ... timed out". This can be
>>>> fixed by disable the REG_TXPAUSE.
>>>>
>>>> Signed-off-by: Jun ASAKA <JunASAKA@...040330.moe>
>>>> ---
>>>>  drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8192e.c | 5 +++++
>>>>  1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8192e.c
>>>> b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8192e.c
>>>> index a7d76693c02d..9d0ed6760cb6 100644
>>>> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8192e.c
>>>> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8192e.c
>>>> @@ -1744,6 +1744,11 @@ static void rtl8192e_enable_rf(struct rtl8xxxu_priv *priv)
>>>>  	val8 = rtl8xxxu_read8(priv, REG_PAD_CTRL1);
>>>>  	val8 &= ~BIT(0);
>>>>  	rtl8xxxu_write8(priv, REG_PAD_CTRL1, val8);
>>>> +
>>>> +	/*
>>>> +	 * Fix transmission failure of rtl8192e.
>>>> +	 */
>>>> +	rtl8xxxu_write8(priv, REG_TXPAUSE, 0x00);
>>>
>>> I trace when rtl8xxxu set REG_TXPAUSE=0xff that will stop TX.
>>> The occasions include RF calibration, LPS mode (called by power off), and
>>> going to stop. So, I think RF calibration does TX pause but not restore
>>> settings after calibration, and causes TX stuck. As the flow I traced,
>>> this patch looks reasonable. But, I wonder why other people don't meet
>>> this problem.
>>>
>> Other people have this problem too:
>> https://bugzilla.kernel.org/show_bug.cgi?id=196769
>> https://bugzilla.kernel.org/show_bug.cgi?id=216746
> 
> In the threads, you have answered my question with
> "kernel 4.8.0 works, but 4.9.? does not work."
> 
>>
>> The RF calibration does restore REG_TXPAUSE at the end. What happens is
>> when you plug in the device, something (mac80211? wpa_supplicant?) calls
>> rtl8xxxu_start(), then rtl8xxxu_stop(), then rtl8xxxu_start() again.
>> rtl8xxxu_stop() sets REG_TXPAUSE to 0xff and nothing sets it back to 0.
>>
> 
> You are correct. That is clear to me. I miss the point that RF calibration
> does backup/restore registers containing REG_TXPAUSE.
> 
> Then, I think my reviewed-by can be still applied, right?
> 
> Ping-Ke
> 
Yes.