linux-kernel - Re: [PATCH] net: usb: lan78xx: add weak dependency with micrel phy module

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Message-ID: <931b582808f237aa3746c5b0a96b3665@manjaro.org>
Date: Sat, 27 Jul 2024 19:15:26 +0200
From: Dragan Simic <dsimic@...jaro.org>
To: Andrew Lunn <andrew@...n.ch>
Cc: Jose Ignacio Tornos Martinez <jtornosm@...hat.com>,
 UNGLinuxDriver@...rochip.com, davem@...emloft.net, edumazet@...gle.com,
 f.fainelli@...il.com, gregkh@...uxfoundation.org, kuba@...nel.org,
 linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-usb@...r.kernel.org, lucas.demarchi@...el.com, masahiroy@...nel.org,
 mcgrof@...nel.org, netdev@...r.kernel.org, pabeni@...hat.com,
 woojung.huh@...rochip.com
Subject: Re: [PATCH] net: usb: lan78xx: add weak dependency with micrel phy
 module

Hello,

On 2024-07-26 22:59, Andrew Lunn wrote:
> On Fri, Jul 26, 2024 at 02:15:26PM +0200, Jose Ignacio Tornos Martinez 
> wrote:
>> Hello Andrew,
>> 
>> > What this does appear to do is differentiate between 'pre' which will
>> > load the kernel module before it is requested. Since there is no 'pre'
>> > for this, it seems pointless whacking this mole.
>> 
>> Precisely, we need to fix the lan78xx case with micrel phy (and other
>> possible phy modules) too, due to the commented issue generating 
>> initramfs
>> in order to include the phy module.
> 
> I still don't see how this solves any issues with generating the
> initramfs.
> 
> There are more than 200 Ethernet drivers, and around 75 PHY
> drivers. If this patch is merged, you have one MAC driver indicating
> it needs one PHY driver. There is nothing much you can do with that
> information. You need to wait until 99% of the MAC drivers indicate
> which PHY drivers are needed. Then you can use this information leave
> out any PHY which is not needed, and hope you only break a small
> number of devices. But even if you wait 20 years i doubt you will get
> 99% of the MAC drivers indicating what PHY drivers you need.  Because
> nothing really uses this information today.
> 
> So as far as i see, this has nothing to do with building the
> initramfs.

Before going into explaining my viewpoint, could someone, please, 
clarify
which LAN78xx USB-to-Ethernet bridge does this apply to?  I already had
a look at a few LAN78xx datasheets, and I'm not sure how the external 
PHY
becomes exposed over the USB interface, so it needs a driver.