netdev - Re: [PATCH v3 net 1/3] net: mediatek: sgmii: ensure the SGMII PHY is powered down on configuration

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Message-ID: <Y8/S4eAK338MG53B@shell.armlinux.org.uk>
Date:   Tue, 24 Jan 2023 12:45:21 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     Bjørn Mork <bjorn@...k.no>,
        netdev@...r.kernel.org, Felix Fietkau <nbd@....name>,
        John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Daniel Golle <daniel@...rotopia.org>,
        Alexander Couzens <lynxis@...0.eu>
Subject: Re: [PATCH v3 net 1/3] net: mediatek: sgmii: ensure the SGMII PHY is
 powered down on configuration

On Tue, Jan 24, 2023 at 01:19:15PM +0100, Paolo Abeni wrote:
> On Sun, 2023-01-22 at 22:21 +0100, Bjørn Mork wrote:
> > From: Alexander Couzens <lynxis@...0.eu>
> > 
> > The code expect the PHY to be in power down which is only true after reset.
> > Allow changes of the SGMII parameters more than once.
> > 
> > Only power down when reconfiguring to avoid bouncing the link when there's
> > no reason to - based on code from Russell King.
> > 
> > There are cases when the SGMII_PHYA_PWD register contains 0x9 which
> > prevents SGMII from working. The SGMII still shows link but no traffic
> > can flow. Writing 0x0 to the PHYA_PWD register fix the issue. 0x0 was
> > taken from a good working state of the SGMII interface.
> 
> This looks like a legitimate fix for -net, but we need a suitable Fixes
> tag pointing to the culprit commit.
> 
> Please repost including such tag. While at that you could also consider
> including Simon's suggestion.
> 
> The following 2 patches looks like new features/refactor that would be
> more suitable for net-next, and included here due to the code
> dependency.

I'm not sure why you think that, especially for patch 2.

Patch 2 corrects the sense of the duplex bit - the code originally
set this for full duplex, but in actual fact, the bit needs to be set
for half duplex. I can't see how one could regard that as a feature
or a refactor.

I'm also not sure how you could regard patch 3 as a refactor. It
could be argued that it is a new feature, but it is actually a bug
fix for the patch converting the driver to phylink_pcs which
omitted setting this, making the pcs_get_state() method rather
useless.

So I regard all three patches as fixes, not features or refactoring.

-- 
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