linux-kernel - Re: [RFC PATCH net-next 5/8] net: phy: realtek: use phy_read

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Message-ID: <d7eaf73b-282a-df7d-d9a5-530e431701a1@gmail.com>
Date:   Sat, 22 Apr 2023 17:11:57 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Daniel Golle <daniel@...rotopia.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Chen Minqiang <ptpt52@...il.com>, Chukun Pan <amadeus@....edu.cn>,
        Yevhen Kolomeiko <jarvis2709@...il.com>,
        Alexander Couzens <lynxis@...0.eu>
Subject: Re: [RFC PATCH net-next 5/8] net: phy: realtek: use phy_read_paged
 instead of open coding

On 22.04.2023 13:48, Daniel Golle wrote:
> Instead of open coding a paged read, use the phy_read_paged function
> in rtlgen_supports_2_5gbps.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>  drivers/net/phy/realtek.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
> index f97b5e49fae58..62fb965b6d338 100644
> --- a/drivers/net/phy/realtek.c
> +++ b/drivers/net/phy/realtek.c
> @@ -735,9 +735,7 @@ static bool rtlgen_supports_2_5gbps(struct phy_device *phydev)
>  {
>  	int val;
>  
> -	phy_write(phydev, RTL821x_PAGE_SELECT, 0xa61);
> -	val = phy_read(phydev, 0x13);
> -	phy_write(phydev, RTL821x_PAGE_SELECT, 0);
> +	val = phy_read_paged(phydev, 0xa61, 0x13);
>  
>  	return val >= 0 && val & RTL_SUPPORTS_2500FULL;
>  }

I remember I had a reason to open-code it, it took me some minutes
to recall it.
phy_read_paged() calls __phy_read_page() that relies on phydev->drv
being set. phydev->drv is set in phy_probe(). And probing is done
after matching. __phy_read_paged() should have given you a warning.
Did you test this patch? If yes and you didn't get the warning,
then apparently I miss something.