linux-kernel - Re: [PATCH net] net: phy: mxl-gpy: fix bogus error on USXGMII and integrated PHY

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Message-ID: <aR8pHpceYe16L9Ey@shell.armlinux.org.uk>
Date: Thu, 20 Nov 2025 14:43:42 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Daniel Golle <daniel@...rotopia.org>
Cc: Xu Liang <lxu@...linear.com>, Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Raju Lakkaraju <Raju.Lakkaraju@...rochip.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: phy: mxl-gpy: fix bogus error on USXGMII and
 integrated PHY

On Thu, Nov 20, 2025 at 02:17:13PM +0000, Daniel Golle wrote:
> As the interface mode doesn't need to be updated on PHYs connected with
> USXGMII and integrated PHYs, gpy_update_interface() should just return 0
> in these cases rather than -EINVAL which has wrongly been introduced by
> commit 7a495dde27ebc ("net: phy: mxl-gpy: Change gpy_update_interface()
> function return type"), as this breaks support for those PHYs.

I think there's more problems here. gpy_update_interface() does more
than just updating the interface, it also reads the master/slave and
mdix state at the end of the function. Returning early for interfaces
we don't means that we don't wish to update the interface for means
these don't get read. Since these are media-side and are irrespective
of the host-side interface, this seems buggy.

So, while this patch is correct, I think it would make sense to also
fix the other problems here.

Reviewed-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Thanks!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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