netdev - Re: [PATCH] wifi: rtl8xxxu: fix authentication timeout due to incorrect RCR value

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Date:   Thu, 27 Apr 2023 13:01:40 -0500
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Yun Lu <luyun_611@....com>, 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
Subject: Re: [PATCH] wifi: rtl8xxxu: fix authentication timeout due to
 incorrect RCR value

On 4/26/23 21:05, Yun Lu wrote:
> From: Yun Lu <luyun@...inos.cn>
> 
> When using rtl8192cu with rtl8xxxu driver to connect wifi, there is a
> probability of failure, which shows "authentication with ... timed out".
> Through debugging, it was found that the RCR register has been inexplicably
> modified to an incorrect value, resulting in the nic not being able to
> receive authenticated frames.
> 
> To fix this problem, add regrcr in rtl8xxxu_priv struct, and store
> the RCR value every time the register is writen, and use it the next
> time the register need to be modified.
> 
> Signed-off-by: Yun Lu <luyun@...inos.cn>
> ---
>   drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h      | 1 +
>   drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 4 +++-
>   2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> index c8cee4a24755..4088aaa1c618 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> @@ -1518,6 +1518,7 @@ struct rtl8xxxu_priv {
>   	u32 rege9c;
>   	u32 regeb4;
>   	u32 regebc;
> +	u32 regrcr;
>   	int next_mbox;
>   	int nr_out_eps;
>   
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> index 620a5cc2bfdd..2fe71933ba08 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> @@ -4053,6 +4053,7 @@ static int rtl8xxxu_init_device(struct ieee80211_hw *hw)
>   		RCR_ACCEPT_MGMT_FRAME | RCR_HTC_LOC_CTRL |
>   		RCR_APPEND_PHYSTAT | RCR_APPEND_ICV | RCR_APPEND_MIC;
>   	rtl8xxxu_write32(priv, REG_RCR, val32);
> +	priv->regrcr = val32;
>   
>   	if (priv->rtl_chip == RTL8188F) {
>   		/* Accept all data frames */
> @@ -6273,7 +6274,7 @@ static void rtl8xxxu_configure_filter(struct ieee80211_hw *hw,
>   				      unsigned int *total_flags, u64 multicast)
>   {
>   	struct rtl8xxxu_priv *priv = hw->priv;
> -	u32 rcr = rtl8xxxu_read32(priv, REG_RCR);
> +	u32 rcr = priv->regrcr;
>   
>   	dev_dbg(&priv->udev->dev, "%s: changed_flags %08x, total_flags %08x\n",
>   		__func__, changed_flags, *total_flags);
> @@ -6319,6 +6320,7 @@ static void rtl8xxxu_configure_filter(struct ieee80211_hw *hw,
>   	 */
>   
>   	rtl8xxxu_write32(priv, REG_RCR, rcr);
> +	priv->regrcr = rcr;
>   
>   	*total_flags &= (FIF_ALLMULTI | FIF_FCSFAIL | FIF_BCN_PRBRESP_PROMISC |
>   			 FIF_CONTROL | FIF_OTHER_BSS | FIF_PSPOLL |

Wouldn't it be better to find the location that is writing the incorrect value 
to RCR and fix that? It seems to me that you are applying a band-aid rather than 
fixing the problem.

Larry