netdev - Re: [PATCH net v5 0/4] net: phy: bcm54811: Fix the PHY initialization

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Message-ID: <414cc1ef-0c3a-4228-8d59-6ef29aedc51c@axis.com>
Date: Fri, 4 Jul 2025 10:35:07 +0200
From: Kamil Horák (2N) <kamilh@...s.com>
To: Paolo Abeni <pabeni@...hat.com>,
 Florian Fainelli <florian.fainelli@...adcom.com>,
 Jakub Kicinski <kuba@...nel.org>
Cc: bcm-kernel-feedback-list@...adcom.com, andrew@...n.ch,
 hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
 edumazet@...gle.com, krzk+dt@...nel.org, conor+dt@...nel.org,
 netdev@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, robh@...nel.org, andrew+netdev@...n.ch,
 horms@...nel.org, corbet@....net, linux-doc@...r.kernel.org
Subject: Re: [PATCH net v5 0/4] net: phy: bcm54811: Fix the PHY initialization



On 7/3/25 12:03, Paolo Abeni wrote:
> On 7/3/25 11:03 AM, Kamil Horák (2N) wrote:
>> On 7/3/25 01:46, Florian Fainelli wrote:
>>> On 7/2/25 15:02, Jakub Kicinski wrote:
>>>> On Tue, 1 Jul 2025 09:50:11 +0200 Kamil Horák - 2N wrote:
>>>>> PATCH 1 - Add MII-Lite PHY interface mode as defined by Broadcom for
>>>>>      their two-wire PHYs. It can be used with most Ethernet controllers
>>>>>      under certain limitations (no half-duplex link modes etc.).
>>>>>
>>>>> PATCH 2 - Add MII-Lite PHY interface type
>>>>>
>>>>> PATCH 3 - Activation of MII-Lite interface mode on Broadcom bcm5481x
>>>>>      PHYs
>>>>>
>>>>> PATCH 4 - Fix the BCM54811 PHY initialization so that it conforms
>>>>>      to the datasheet regarding a reserved bit in the LRE Control
>>>>>      register, which must be written to zero after every device reset.
>>>>>      Also fix the LRE Status register reading, there is another bit to
>>>>>      be ignored on bcm54811.
>>>>
>>>> I'm a bit lost why the first 3 patches are included in a series for net.
>>>> My naive reading is we didn't support this extra mode, now we do,
>>>> which sounds like a new feature.. Patch 4, sure, but the dependency
>>>> is not obvious.
>>>
>>> I don't see the dependency either, at least not in an explicit way.
>>> Kamil, could patch #4 stand on its own and routed through "net" while
>>> patches 1-3 are routed through "net-next"?
>> It can be done this way, however, even the patch #3 is effectively a
>> fix, not new feature, because the bcm54811 PHY in MLP package only has
>> MII-Lite interface available externally. As far I know, there is no BGA
>> casing available for bcm54811 (unlike bcm54810, that one having both MLP
>> and BGA). Thus, it cannot function without being switched to MII-Lite
>> mode. The introduction of MII-Lite itself is clearly a new feature and
>> it is even (theoretically) available for any MII-capable PHY. So if
>> putting it all to net it is really impossible or contrary to the
>> net-next vs. net selection rules, let's divide it....
>> To get fully functional, bcm54811-based networking, all patches are
>> necessary so any other user out there must wait for both branches to join.
> 
> The above makes sense to me, but I think it would be nice to capture
> some of this info in the cover letter - the fact that many people were
> confused by the series is an hint the info was indeed missing and required.
OK, tried to write more about it
> 
> Please resubmit with an extended cover letter, thanks!
> (unless Florian jumps in and explicitly asks for something different :-P)
> 
No such request appeared since yesterday, so submitting an updated text 
version

> Paolo
> 


Kamil