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

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Message-ID: <192a31a9-ea33-0c51-6549-0525fd3a5b4e@zzy040330.moe>
Date:   Tue, 20 Dec 2022 21:48:47 +0800
From:   Jun ASAKA <JunASAKA@...040330.moe>
To:     Bitterblue Smith <rtl8821cerfe2@...il.com>,
        Ping-Ke Shih <pkshih@...ltek.com>,
        "Jes.Sorensen@...il.com" <Jes.Sorensen@...il.com>
Cc:     "kvalo@...nel.org" <kvalo@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] wifi: rtl8xxxu: fixing transmisison failure for rtl8192eu

On 20/12/2022 21:03, 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
Actually, one of the two bug was issued by me. Also, my friend who is 
using a TP-Link rtl8192eu device said that his device doesn't work as well.
>
> 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.