linux-kernel - Re: [PATCH net-next] net: mscc: simplify retrieving the tag type from the frame header

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Message-ID: <20180716141712.GA5983@piout.net>
Date:   Mon, 16 Jul 2018 16:17:12 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Antoine Tenart <antoine.tenart@...tlin.com>
Cc:     davem@...emloft.net, f.fainelli@...il.com, andrew@...n.ch,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        thomas.petazzoni@...tlin.com, quentin.schulz@...tlin.com,
        allan.nielsen@...rosemi.com
Subject: Re: [PATCH net-next] net: mscc: simplify retrieving the tag type
 from the frame header

On 13/07/2018 16:57:57+0200, Antoine Ténart wrote:
> The tag type in the frame extraction header is only a bit wide. There's
> no need to use GENMASK when retrieving the information. This patch
> simplify the code by dropping GENMASK and using BIT instead.
> 
> Signed-off-by: Antoine Tenart <antoine.tenart@...tlin.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@...tlin.com>

> ---
>  drivers/net/ethernet/mscc/ocelot_board.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mscc/ocelot_board.c b/drivers/net/ethernet/mscc/ocelot_board.c
> index 18df7d934e81..26bb3b18f3be 100644
> --- a/drivers/net/ethernet/mscc/ocelot_board.c
> +++ b/drivers/net/ethernet/mscc/ocelot_board.c
> @@ -29,7 +29,7 @@ static int ocelot_parse_ifh(u32 *ifh, struct frame_info *info)
>  	info->port = (ifh[2] & GENMASK(14, 11)) >> 11;
>  
>  	info->cpuq = (ifh[3] & GENMASK(27, 20)) >> 20;
> -	info->tag_type = (ifh[3] & GENMASK(16, 16)) >> 16;
> +	info->tag_type = (ifh[3] & BIT(16)) >> 16;
>  	info->vid = ifh[3] & GENMASK(11, 0);
>  
>  	return 0;
> -- 
> 2.17.1
> 

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com