netdev - Re: [PATCH v2 1/2] net: macb: Clean up macb

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Message-ID: <fb672897-92dd-4311-eed2-1cd5a7f6e591@seco.com>
Date:   Mon, 25 Oct 2021 11:26:28 -0400
From:   Sean Anderson <sean.anderson@...o.com>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     Antoine Tenart <atenart@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: Re: [PATCH v2 1/2] net: macb: Clean up macb_validate



On 10/25/21 6:35 AM, Russell King (Oracle) wrote:
> On Fri, Oct 22, 2021 at 01:37:34PM -0400, Sean Anderson wrote:
>> Hi Russell,
>>
>> For "net: phy: add phy_interface_t bitmap support", phylink_or would be
>> nice as well. I use it when implementing NA support for PCSs.
>
> I think you actually mean phy_interface_or(). Given that we will need
> MAC drivers to provide the union of their PCS support, I think that
> would be a sensible addition. Thanks.
>
>> For "net: sfp: augment SFP parsing with phy_interface_t bitmap",
>> drivers/net/phy/marvell.c also needs to be converted. This is due to
>> b697d9d38a5a ("net: phy: marvell: add SFP support for 88E1510") being
>> added to net-next/master.
>>
>> (I think you have fixed this in your latest revision)
>
> I haven't - but when I move the patch series onto net-next, that will
> need to be updated.
>
>> "net: phylink: use supported_interfaces for phylink validation" looks
>> good. Though the documentation should be updated. Perhaps something
>> like
>
> Yes, I haven't bothered with the doc updates yet... they will need to
> be done before the patches are ready. Thanks for the suggestions though.
>
>> I think "net: macb: populate supported_interfaces member" is wrong.
>> Gigabit modes should be predicated on GIGABIT_MODE_AVAILABLE.
>
> It is a conversion of what macb_validate() does - if the conversion is
> incorrect, then macb_validate() is incorrect.
>
> If MACB_CAPS_GIGABIT_MODE_AVAILABLE isn't set, but MACB_CAPS_HIGH_SPEED
> and MACB_CAPS_PCS are both set, macb_validate() will not zero the
> supported mask if e.g. PHY_INTERFACE_MODE_10GBASER is requested - it
> will indicate 10baseT and 100baseT speeds are supported. So the current
> macb_validate() code basically tells phylink that
> PHY_INTERFACE_MODE_10GBASER supports 10baseT and 100baseT speeds!
>
> This probably is not what is intended, but this is what the code does,
> and I'm maintaining bug-compatibility with the current macb_validate()
> implementation. Any changes to the behaviour should be a separate
> patch - either fixing it before this patch, or fixing it afterwards.
> As the series is currently based on v5.14, it may be that this has
> already been fixed.

Ugh. This sort of thing is what I wanted to address in the first place.
The current logic lends itself well to these sorts of errors.

--Sean