linux-kernel - Re: [PATCH] rtlwifi:rtl_watchdog_wq_callback: fix calling rtl_lps_enter|rtl_lps

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Date:	Mon, 2 May 2016 10:40:34 -0500
From:	Larry Finger <Larry.Finger@...inger.net>
To:	Wang YanQing <udknight@...il.com>, kvalo@...eaurora.org,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtlwifi:rtl_watchdog_wq_callback: fix calling
 rtl_lps_enter|rtl_lps_leave in opposite condition

On 05/02/2016 12:37 AM, Wang YanQing wrote:
> Commit a269913c52ad37952a4d9953bb6d748f7299c304
> ("rtlwifi: Rework rtl_lps_leave() and rtl_lps_enter() to use work queue")
> make a mistake, change the meaning of num_tx|rx_inperiod comparison test.
>
> Commit fd09ff958777cf583d7541f180991c0fc50bd2f7
> ("rtlwifi: Remove extra workqueue for enter/leave power state")
> follow previous mistake, bring us to current code.
>
> This patch fix it.
>
> Signed-off-by: Wang YanQing <udknight@...il.com>
> ---
>   I think this patch should be ported back to stable kernels, 3.10+.
>   In my machine, I will lost wifi connection after minutes if I enable
>   fwlps.
>
>   drivers/net/wireless/realtek/rtlwifi/base.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/realtek/rtlwifi/base.c b/drivers/net/wireless/realtek/rtlwifi/base.c
> index c74eb13..264466f 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/base.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/base.c
> @@ -1660,9 +1660,9 @@ void rtl_watchdog_wq_callback(void *data)
>   		if (((rtlpriv->link_info.num_rx_inperiod +
>   		      rtlpriv->link_info.num_tx_inperiod) > 8) ||
>   		    (rtlpriv->link_info.num_rx_inperiod > 2))
> -			rtl_lps_enter(hw);
> -		else
>   			rtl_lps_leave(hw);
> +		else
> +			rtl_lps_enter(hw);
>   	}
>
>   	rtlpriv->link_info.num_rx_inperiod = 0;
>

NACK

This patch is correct. There is a logic error in entering/exiting power-save 
mode. Thus the code part is OK; however, the subject and commit message need to 
be improved. If I had prepared this patch, my subject would have been "rtlwifi: 
Fix logic error in enter/exit power-save mode". For the commit message, I would 
have used the following:

In commit fd09ff958777 ("rtlwifi: Remove extra workqueue for enter/leave power 
state"), the tests for enter/exit power-save mode were inverted. With this 
change applied, the wifi connection becomes much more stable.

Fixes: fd09ff958777 ("rtlwifi: Remove extra workqueue for enter/leave power state")
Signed-off-by: Wang YanQing <udknight@...il.com>
CC: Stable <stable@...r.kernel.org> [3.10+]
---

Thanks for finding this problem.

Larry