netdev - Re: [PATCH v1 1/2] modpost: file2alias: fixup mdio alias garbled code in modules.alias

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Date:   Tue, 23 Nov 2021 05:12:30 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     zhuyinbo <zhuyinbo@...ngson.cn>
Cc:     Heiner Kallweit <hkallweit1@...il.com>, linux@...linux.org.uk,
        davem@...emloft.net, kuba@...nel.org, masahiroy@...nel.org,
        michal.lkml@...kovi.net, ndesaulniers@...gle.com,
        netdev@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] modpost: file2alias: fixup mdio alias garbled
 code in modules.alias

On Tue, Nov 23, 2021 at 09:33:03AM +0800, zhuyinbo wrote:
> 
> 在 2021/11/22 下午10:07, Andrew Lunn 写道:
> 
>     On Mon, Nov 22, 2021 at 08:14:57PM +0800, Yinbo Zhu wrote:
> 
>         After module compilation, module alias mechanism will generate a ugly
>         mdio modules alias configure if ethernet phy was selected, this patch
>         is to fixup mdio alias garbled code.
> 
>         In addition, that ugly alias configure will cause ethernet phy module
>         doens't match udev, phy module auto-load is fail, but add this patch
>         that it is well mdio driver alias configure match phy device uevent.
> 
>     What PHY do you have problems with? What is the PHY id and which
>     driver should be loaded.
> 
>     This code has existed a long time, so suddenly saying it is wrong and
>     changing it needs a good explanation why it is wrong. Being ugly is
>     not a good reason.
> 
>         Andrew
> 
> Hi Andrew,
> 
>     Use default mdio configure, After module compilation, mdio alias configure
> is following and it doesn't match
> 
>     the match phy dev(mdio dev)  uevent, because the mdio alias configure 
> "0000000101000001000011111001????"  include "?" and

A PHY ID generally break up into 3 parts.

The OUI of the manufacture.
The device.
The revision

The ? means these bits don't matter. Those correspond to the
revision. Generally, a driver can driver any revision of the PHY,
which is why those bits don't matter.

So when a driver probes with the id 00000001010000010000111110010110
we expect user space to find the best match, performing wildcard
expansion. So the ? will match anything.

Since this is worked for a long time, do you have an example where it
is broken? If so, which PHY driver? If it is broken, no driver is
loaded, or the wrong driver is loaded, i expect it is a bug in a
specific driver. And we should fix that bug in the specific driver.

     Andrew