netdev - Re: [PATCH RFC net-next v2 3/8] net: stmmac: dwmac1000: convert sgmii/rgmii "pcs" to phylink

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Date: Wed, 12 Jun 2024 23:04:11 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Serge Semin <fancer.lancer@...il.com>
Cc: Andrew Halaney <ahalaney@...hat.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RFC net-next v2 3/8] net: stmmac: dwmac1000: convert
 sgmii/rgmii "pcs" to phylink

On Tue, Jun 11, 2024 at 03:25:14PM +0300, Serge Semin wrote:
> Hi Russell, Andrew
>
> Should we have a DW IP-core-specific getter like
> stmmac_ops::pcs_get_config_reg() which would return the
> tx_config_reg[15:0] field then we could have cleared the IRQ by just
> calling it, we could have had the fields generically
> parsed in the dwmac_pcs_isr() handler and in the
> phylink_pcs_ops::pcs_get_state().

pcs_get_state() is not supposed to get some cached state, but is
supposed to return the real state at the time that it is called.

There's a good reason for this - dealing with latched-low link failed
indications, it's necessary that pcs_get_state() reports that the link
failed if _sometime_ between the last time it was called and the next
time the link has failed.

So, I'm afraid your idea of simplifying it doesn't sound to me like a
good idea.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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