linux-kernel - Re: [PATCH v4 09/13] wifi: brcm80211: Replace open-coded parity calculation with parity

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Message-ID: <20250415161337.GZ395307@horms.kernel.org>
Date: Tue, 15 Apr 2025 17:13:37 +0100
From: Simon Horman <horms@...nel.org>
To: Kuan-Wei Chiu <visitorckw@...il.com>
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	Yu-Chun Lin <eleanor15x@...il.com>
Subject: Re: [PATCH v4 09/13] wifi: brcm80211: Replace open-coded parity
 calculation with parity_odd()

On Wed, Apr 09, 2025 at 11:43:52PM +0800, Kuan-Wei Chiu wrote:
> Refactor parity calculations to use the standard parity_odd() helper.
> This change eliminates redundant implementations.
> 
> Co-developed-by: Yu-Chun Lin <eleanor15x@...il.com>
> Signed-off-by: Yu-Chun Lin <eleanor15x@...il.com>
> Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
> Acked-by: Arend van Spriel <arend.vanspriel@...adcom.com>
> ---
>  .../wireless/broadcom/brcm80211/brcmsmac/dma.c | 18 ++----------------
>  1 file changed, 2 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/dma.c b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/dma.c
> index 80c35027787a..5d7500ee2d3b 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/dma.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/dma.c
> @@ -17,6 +17,7 @@
>  #include <linux/slab.h>
>  #include <linux/delay.h>
>  #include <linux/pci.h>
> +#include <linux/bitops.h>
>  #include <net/cfg80211.h>
>  #include <net/mac80211.h>
>  
> @@ -283,24 +284,9 @@ struct dma_info {
>  	bool aligndesc_4k;
>  };
>  
> -/* Check for odd number of 1's */
> -static u32 parity32(__le32 data)
> -{
> -	/* no swap needed for counting 1's */
> -	u32 par_data = *(u32 *)&data;
> -
> -	par_data ^= par_data >> 16;
> -	par_data ^= par_data >> 8;
> -	par_data ^= par_data >> 4;
> -	par_data ^= par_data >> 2;
> -	par_data ^= par_data >> 1;
> -
> -	return par_data & 1;
> -}
> -
>  static bool dma64_dd_parity(struct dma64desc *dd)
>  {
> -	return parity32(dd->addrlow ^ dd->addrhigh ^ dd->ctrl1 ^ dd->ctrl2);
> +	return parity_odd(dd->addrlow ^ dd->addrhigh ^ dd->ctrl1 ^ dd->ctrl2);
>  }

parity32 expected a little-endian integer as it's argument
while parity_odd expects a host byte order value.

I realise that the existing code just casts-away the endianness
annotation, but this patch adds a Sparse warning.

 .../brcmsmac/dma.c:289:66: warning: incorrect type in argument 1 (different base types)
 .../brcmsmac/dma.c:289:66:    expected unsigned long long [usertype] val
 .../brcmsmac/dma.c:289:66:    got restricted __le32

>  
>  /* descriptor bumping functions */
> -- 
> 2.34.1
> 
>