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Date:   Fri, 19 May 2023 10:01:26 +0200
From:   Simon Horman <simon.horman@corigine.com>
To:     Min-Hua Chen <minhuadotchen@gmail.com>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: stmmac: use le32_to_cpu for p->des0 and p->des1
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References: <20230519002522.3648-1-minhuadotchen@gmail.com>
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On Fri, May 19, 2023 at 08:25:21AM +0800, Min-Hua Chen wrote:
> Use le32_to_cpu for p->des0 and p->des1 to fix the
> following sparse warnings:
> 
> drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c:110:23: sparse: warning: restricted __le32 degrades to integer
> drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c:110:50: sparse: warning: restricted __le32 degrades to integer
> 
> Signed-off-by: Min-Hua Chen <minhuadotchen@gmail.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c
> index 13c347ee8be9..3d094d83e975 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c
> @@ -107,7 +107,8 @@ static int dwxgmac2_rx_check_timestamp(void *desc)
>  	ts_valid = !(rdes3 & XGMAC_RDES3_TSD) && (rdes3 & XGMAC_RDES3_TSA);
>  
>  	if (likely(desc_valid && ts_valid)) {
> -		if ((p->des0 == 0xffffffff) && (p->des1 == 0xffffffff))
> +		if ((le32_to_cpu(p->des0) == 0xffffffff) &&
> +		    (le32_to_cpu(p->des1) == 0xffffffff))

Hi Min-Hua Chen,

I'm not sure if it makes a meaningful difference in practice - and
certainly it won't on LE systems. But I wonder if it's nicer to do the
conversion on the constant rather than the variable part of the comparison.

		if ((p->des0 == cpu_to_le32(0xffffffff)) &&
		    (p->des1 == cpu_to_le32(0xffffffff)))

>  			return -EINVAL;
>  		return 0;
>  	}
> -- 
> 2.34.1
> 
>