netdev - Re: [PATCH net-next 0/15] Add and use helper for PCS negotiation modes

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Message-ID: <20230620112512.ikhdjt7hm34xespo@skbuf>
Date: Tue, 20 Jun 2023 14:25:12 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Alexander Couzens <lynxis@...0.eu>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Cc@....codeaurora.org:Claudiu Beznea <claudiu.beznea@...rochip.com>,
	Daniel Golle <daniel@...rotopia.org>,
	Daniel Machon <daniel.machon@...rochip.com>,
	"David S. Miller" <davem@...emloft.net>,
	DENG Qingfang <dqfext@...il.com>, Eric Dumazet <edumazet@...gle.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Ioana Ciornei <ioana.ciornei@....com>,
	Jakub Kicinski <kuba@...nel.org>,
	Jose Abreu <Jose.Abreu@...opsys.com>,
	Landen Chao <Landen.Chao@...iatek.com>,
	Lars Povlsen <lars.povlsen@...rochip.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	Madalin Bucur <madalin.bucur@....com>,
	Marcin Wojtas <mw@...ihalf.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Michal Simek <michal.simek@....com>, netdev@...r.kernel.org,
	Nicolas Ferre <nicolas.ferre@...rochip.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>,
	Sean Anderson <sean.anderson@...o.com>,
	Sean Wang <sean.wang@...iatek.com>,
	Steen Hegelund <Steen.Hegelund@...rochip.com>,
	Taras Chornyi <taras.chornyi@...ision.eu>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH net-next 0/15] Add and use helper for PCS negotiation
 modes

On Fri, Jun 16, 2023 at 04:52:21PM +0100, Russell King (Oracle) wrote:
> I should also add... yes, I did _then_ subsequently use the microchip
> driver as a justification for it. I probably should've explained it
> without using that as justification.
> 
> I could also have used the sja1105 driver as well, since:
> 
> 	MLO_AN_INBAND => PHYLINK_PCS_NEG_INBAND_ENABLED

Technically this should have been:

	MLO_AN_INBAND => neg_mode & PHYLINK_PCS_NEG_INBAND, which
	includes both INBAND_DISABLED and INBAND_ENABLED, right?

> 	MLO_AN_FIXED || MLO_AN_PHY => PHYLINK_PCS_NEG_OUTBAND
> 
> are the conversions done there, which fits with:
> 
> -               if (!phylink_autoneg_inband(mode)) {
> +               if (neg_mode == PHYLINK_PCS_NEG_OUTBAND) {
> 
> since the opposite of !inband is outband.

The conversion is correct - no doubt about it.

Maybe the SJA1105 and its use of the XPCS is also not the best example,
because it doesn't support 1000BASE-X. So it doesn't have to handle the
INBAND_DISABLED state. If it did, the !phylink_autoneg_inband(mode)
check would have been incorrect (insufficient to detect the xpcs state
that it's restoring).