netdev - Re: [PATCH] mt7601u: phy: simplify zero check on val

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Date:   Fri, 20 Sep 2019 15:58:17 +0200
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Jakub Kicinski <kubakici@...pl>, Kalle Valo <kvalo@...eaurora.org>,
        "David S . Miller" <davem@...emloft.net>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mt7601u: phy: simplify zero check on val

> From: Colin Ian King <colin.king@...onical.com>
> 
> Currently the zero check on val to break out of a loop
> is a little obscure.  Replace the val is zero and break check
> with a loop while value is non-zero.
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/net/wireless/mediatek/mt7601u/phy.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
> index 06f5702ab4bd..4e0e473caae1 100644
> --- a/drivers/net/wireless/mediatek/mt7601u/phy.c
> +++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
> @@ -213,9 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)
>  
>  	do {
>  		val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
> -		if (val && ~val)
> -			break;

I think this is not correct since (not considering the cast) we should break
from the loop if val != 0 and val != 0xff, so the right approach I guess is:

diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
index 06f5702ab4bd..d863ab4a66c9 100644
--- a/drivers/net/wireless/mediatek/mt7601u/phy.c
+++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
@@ -213,7 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)
 
 	do {
 		val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
-		if (val && ~val)
+		if (val && val != 0xff)
 			break;
 	} while (--i);

> -	} while (--i);
> +	} while (val && --i);
>  
>  	if (!i) {
>  		dev_err(dev->dev, "Error: BBP is not ready\n");
> -- 
> 2.20.1
> 

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