linux-kernel - Re: [PATCH net-next 1/2] net: phy: aquantia: validate PHY mode on AQR107

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Message-ID: <CAOX2RU7izQLrHQsTK9cFYEGtoE9=xOVTx64o7w-JZpg-+wYvuA@mail.gmail.com>
Date:   Tue, 28 Nov 2023 12:47:46 +0100
From:   Robert Marko <robimarko@...il.com>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     andrew@...n.ch, hkallweit1@...il.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        ansuelsmth@...il.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] net: phy: aquantia: validate PHY mode on AQR107

On Fri, 17 Nov 2023 at 13:46, Russell King (Oracle)
<linux@...linux.org.uk> wrote:
>
> On Fri, Nov 17, 2023 at 11:09:48AM +0100, Robert Marko wrote:
> > The Aquantia driver is not setting the PHY mode itself, but it does however
> > still check if the PHY mode set in DTS is one of the supported modes.
> >
> > However, the set PHY mode does not have to match the actual one, so lets
> > add update the PHY mode during .config_init and warn if they differ.
>
> This looks completely wrong to me. These PHYs can be configured to
> change their MAC-facing interface mode according to the media negotiated
> speed, but you are only checking that _if_ the media is up, then the
> interface that has resulted from that negotiation matches what is in
> DTS. That could be dependent on the link partner, so what works for a
> platform when connected to one link partner may issue your "info"-level
> warning when connected to a different link partner.
>
> So no, this to me looks completely wrong.
>
> You need to check the VEND1_GLOBAL_CFG_* registers, and determine from
> those what interface mode(s) will be used, and then use that to validate
> the mode.
>
> It just so happens that...
>
> http://git.armlinux.org.uk/cgit/linux-arm.git/commit/?h=net-queue&id=f7b531ee8855f81d267a8a42c44da51576f48daf
> http://git.armlinux.org.uk/cgit/linux-arm.git/commit/?h=net-queue&id=f55389aa5d11da8a32dfd65a1b98049878ce09f0
>
> builds a bitmap that can then be tested to check this. Whether the
> above is entirely correct or not, I can't really say, I don't have
> enough information on this PHY.

Hi,
Yeah, I get the issue now.

Nice, those got merged into net-next, so I will iterate by using those.

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