netdev - Re: [PATCH net-next 08/10] net: mdio: Remove unnecessary (void*) conversions

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Date: Thu, 29 Jun 2023 09:59:56 +0800
From: yunchuan <yunchuan@...china.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: iyappan@...amperecomputing.com, keyur@...amperecomputing.com,
 quan@...amperecomputing.com, andrew@...n.ch, hkallweit1@...il.com,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel-janitors@...r.kernel.org
Subject: Re: [PATCH net-next 08/10] net: mdio: Remove unnecessary (void*)
 conversions

On 2023/6/28 17:50, Russell King (Oracle) wrote:
> Hi,
>
> I think you missed one case:
>
>          if (mdio_id == XGENE_MDIO_RGMII) {
>                  mdio_bus->read = xgene_mdio_rgmii_read;
>                  mdio_bus->write = xgene_mdio_rgmii_write;
>                  mdio_bus->priv = (void __force *)pdata;
>
> This cast using __force is also not required.
>
> On Wed, Jun 28, 2023 at 10:45:17AM +0800, wuych wrote:
>> @@ -211,7 +211,7 @@ static void xgene_enet_wr_mdio_csr(void __iomem *base_addr,
>>   static int xgene_xfi_mdio_write(struct mii_bus *bus, int phy_id,
>>   				int reg, u16 data)
>>   {
>> -	void __iomem *addr = (void __iomem *)bus->priv;
>> +	void __iomem *addr = bus->priv;
>>   	int timeout = 100;
>>   	u32 status, val;
>>   
>> @@ -234,7 +234,7 @@ static int xgene_xfi_mdio_write(struct mii_bus *bus, int phy_id,
>>   
>>   static int xgene_xfi_mdio_read(struct mii_bus *bus, int phy_id, int reg)
>>   {
>> -	void __iomem *addr = (void __iomem *)bus->priv;
>> +	void __iomem *addr = bus->priv;
>>   	u32 data, status, val;
>>   	int timeout = 100;
> These probably cause Sparse to warn whether or not the cast is there.

Hi, Russell King,

I didn't notice this Sparse warning.
Should I remove this cast although it cause Sparse warning?
>
> Given that in this case, bus->priv is initialised via:
>
>                  mdio_bus->priv = (void __force *)pdata->mdio_csr_addr;
>
> I think the simple thing is to _always_ initialise mdio_bus->priv
> to point at pdata, and have xgene_xfi_mdio_*() always do:
>
> 	struct xgene_mdio_pdata *pdata = bus->priv;
> 	void __iomem *addr = pdata->mdio_csr_addr;
>
> The extra access will be dwarfed by the time taken to perform the
> access.
>
> This change should be made with a separate patch and not combined with
> the patch removing the casts in xgene_mdio_rgmii_*().
yeah, this change is great.
I will send a separate patch as your suggestion If we can ignore Sparse 
warning.
Thanks for your suggestion!

wuych

>
> Thanks.
>