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Date:   Wed, 21 Dec 2022 14:14:21 +0200
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Subject: Re: [PATCH] wifi: rtl8xxxu: fixing transmisison failure for rtl8192eu
To:     Ping-Ke Shih <pkshih@realtek.com>,
        "Jes.Sorensen@gmail.com" <Jes.Sorensen@gmail.com>,
        "JunASAKA@zzy040330.moe" <JunASAKA@zzy040330.moe>
Cc:     "davem@davemloft.net" <davem@davemloft.net>,
        "kvalo@kernel.org" <kvalo@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "edumazet@google.com" <edumazet@google.com>,
        "pabeni@redhat.com" <pabeni@redhat.com>
References: <20221217030659.12577-1-JunASAKA@zzy040330.moe>
 <3b4124ebabcb4ceaae89cd9ccf84c7de@realtek.com>
 <33b2b585-c5b1-5888-bcee-ca74ce809a44@gmail.com>
 <fb0a7d6c0897464550ed7ee75c6318c525a0f001.camel@realtek.com>
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From:   Bitterblue Smith <rtl8821cerfe2@gmail.com>
In-Reply-To: <fb0a7d6c0897464550ed7ee75c6318c525a0f001.camel@realtek.com>
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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@zzy040330.moe>
>>>> Sent: Saturday, December 17, 2022 11:07 AM
>>>> To: Jes.Sorensen@gmail.com
>>>> Cc: kvalo@kernel.org; davem@davemloft.net; edumazet@google.com; kuba@kernel.org; 
>>>> pabeni@redhat.com;
>>>> linux-wireless@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Jun
>>>> ASAKA
>>>> <JunASAKA@zzy040330.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@zzy040330.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.