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

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Message-ID: <56cb86e1-db38-43c9-857b-f14bb4a5ecd8@redhat.com>
Date: Thu, 3 Jul 2025 12:03:41 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Kamil Horák (2N) <kamilh@...s.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 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.

Please resubmit with an extended cover letter, thanks!
(unless Florian jumps in and explicitly asks for something different :-P)

Paolo