linux-kernel - Re: [PATCH 02/10] brcmstb_gisb: Replace "hweight_long(mask) != 1" with "!is_power_of

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Message-ID: <566F1ECB.8080809@gmail.com>
Date:	Mon, 14 Dec 2015 11:55:55 -0800
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>, computersforpeace@...il.com,
	gregory.0xf0@...il.com, linux-arm-kernel@...ts.infradead.org
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/10] brcmstb_gisb: Replace "hweight_long(mask) != 1"
 with "!is_power_of_2(mask)"

On 06/12/15 02:11, Zhaoxiu Zeng wrote:
> From: Zeng Zhaoxiu <zhaoxiu.zeng@...il.com>

is_power_of_2, AFAICT does not handle the case where the mask to be
tested for is zero, which is why I went with hweight_long() in the first
place.

Without further explanation as to whether we should prefer
is_power_of_2(), NAK.

> 
> Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@...il.com>
> ---
>  drivers/bus/brcmstb_gisb.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/brcmstb_gisb.c b/drivers/bus/brcmstb_gisb.c
> index f364fa4..2816a04 100644
> --- a/drivers/bus/brcmstb_gisb.c
> +++ b/drivers/bus/brcmstb_gisb.c
> @@ -24,6 +24,7 @@
>  #include <linux/of.h>
>  #include <linux/bitops.h>
>  #include <linux/pm.h>
> +#include <linux/log2.h>
>  
>  #ifdef CONFIG_ARM
>  #include <asm/bug.h>
> @@ -171,7 +172,7 @@ brcmstb_gisb_master_to_str(struct brcmstb_gisb_arb_device *gdev,
>  {
>  	u32 mask = gdev->valid_mask & masters;
>  
> -	if (hweight_long(mask) != 1)
> +	if (!is_power_of_2(mask))
>  		return NULL;
>  
>  	return gdev->master_names[ffs(mask) - 1];
> 


-- 
Florian
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