netdev - Re: [PATCH net-next] net: ethernet: et131x: Remove unused variable 'pm

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Date:   Fri, 17 Jul 2020 13:57:27 +0100
From:   Mark Einon <mark.einon@...il.com>
To:     Zhang Changzhong <zhangchangzhong@...wei.com>, davem@...emloft.net,
        kuba@...nel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: ethernet: et131x: Remove unused variable
 'pm_csr'

Hi Zhang,

On Fri, 2020-07-17 at 18:33 +0800, Zhang Changzhong wrote:
> Gcc report warning as follows:
> 
> drivers/net/ethernet/agere/et131x.c:953:6: warning:
>  variable 'pm_csr' set but not used [-Wunused-but-set-variable]
>   953 |  u32 pm_csr;
>       |      ^~~~~~
> drivers/net/ethernet/agere/et131x.c:1002:6:warning:
>  variable 'pm_csr' set but not used [-Wunused-but-set-variable]
>  1002 |  u32 pm_csr;
>       |      ^~~~~~
> drivers/net/ethernet/agere/et131x.c:3446:8: warning:
>  variable 'pm_csr' set but not used [-Wunused-but-set-variable]
>  3446 |    u32 pm_csr;
>       |        ^~~~~~
> 
> After commit 38df6492eb51 ("et131x: Add PCIe gigabit ethernet driver
> et131x to drivers/net"), 'pm_csr' is never used in these functions,
> so removing it to avoid build warning.
> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>
> ---
>  drivers/net/ethernet/agere/et131x.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 

This makes sense, thanks.

The readl() line modified here is also redundant as it gets called from
the subsequent et1310_in_phy_coma() call. A patch to fix this is on it's
way.

Acked-by: Mark Einon <mark.einon@...il.com>

Cheers,

Mark

> diff --git a/drivers/net/ethernet/agere/et131x.c
> b/drivers/net/ethernet/agere/et131x.c
> index 865892c..8806e1e 100644
> --- a/drivers/net/ethernet/agere/et131x.c
> +++ b/drivers/net/ethernet/agere/et131x.c
> @@ -950,7 +950,6 @@ static void
> et1310_setup_device_for_multicast(struct et131x_adapter *adapter)
>  	u32 hash2 = 0;
>  	u32 hash3 = 0;
>  	u32 hash4 = 0;
> -	u32 pm_csr;
>  
>  	/* If ET131X_PACKET_TYPE_MULTICAST is specified, then we
> provision
>  	 * the multi-cast LIST.  If it is NOT specified, (and "ALL" is
> not
> @@ -984,7 +983,7 @@ static void
> et1310_setup_device_for_multicast(struct et131x_adapter *adapter)
>  	}
>  
>  	/* Write out the new hash to the device */
> -	pm_csr = readl(&adapter->regs->global.pm_csr);
> +	readl(&adapter->regs->global.pm_csr);
>  	if (!et1310_in_phy_coma(adapter)) {
>  		writel(hash1, &rxmac->multi_hash1);
>  		writel(hash2, &rxmac->multi_hash2);
> @@ -999,7 +998,6 @@ static void et1310_setup_device_for_unicast(struct
> et131x_adapter *adapter)
>  	u32 uni_pf1;
>  	u32 uni_pf2;
>  	u32 uni_pf3;
> -	u32 pm_csr;
>  
>  	/* Set up unicast packet filter reg 3 to be the first two octets
> of
>  	 * the MAC address for both address
> @@ -1025,7 +1023,7 @@ static void
> et1310_setup_device_for_unicast(struct et131x_adapter *adapter)
>  		  (adapter->addr[4] << ET_RX_UNI_PF_ADDR1_5_SHIFT) |
>  		   adapter->addr[5];
>  
> -	pm_csr = readl(&adapter->regs->global.pm_csr);
> +	readl(&adapter->regs->global.pm_csr);
>  	if (!et1310_in_phy_coma(adapter)) {
>  		writel(uni_pf1, &rxmac->uni_pf_addr1);
>  		writel(uni_pf2, &rxmac->uni_pf_addr2);
> @@ -3443,12 +3441,10 @@ static irqreturn_t et131x_isr(int irq, void
> *dev_id)
>  		 * send a pause packet, otherwise just exit
>  		 */
>  		if (adapter->flow == FLOW_TXONLY || adapter->flow ==
> FLOW_BOTH) {
> -			u32 pm_csr;
> -
>  			/* Tell the device to send a pause packet via
> the back
>  			 * pressure register (bp req and bp xon/xoff)
>  			 */
> -			pm_csr = readl(&iomem->global.pm_csr);
> +			readl(&iomem->global.pm_csr);
>  			if (!et1310_in_phy_coma(adapter))
>  				writel(3, &iomem->txmac.bp_ctrl);
>  		}