netdev - Re: [PATCH net-next 2/5] net: stmmac: intel: remove eee_usecs

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Message-ID: <f8fe981e-3351-469b-9d76-803eb4563932@lunn.ch>
Date: Tue, 8 Apr 2025 20:57:14 +0200
From: Andrew Lunn <andrew@...n.ch>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Jon Hunter <jonathanh@...dia.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Richard Cochran <richardcochran@...il.com>,
	Thierry Reding <treding@...dia.com>
Subject: Re: [PATCH net-next 2/5] net: stmmac: intel: remove eee_usecs_rate
 and hardware write

On Mon, Apr 07, 2025 at 07:58:56PM +0100, Russell King (Oracle) wrote:
> Remove the write to GMAC_1US_TIC_COUNTER for two reasons:
> 
> 1. during initialisation or reinitialisation of the DWMAC core, the
>    core is reset, which sets this register back to its default value.
>    Writing it prior to stmmac_dvr_probe() has no effect.
> 
> 2. Since commit 8efbdbfa9938 ("net: stmmac: Initialize
>    MAC_ONEUS_TIC_COUNTER register"), GMAC4/5 core code will set
>    this register based on the rate of plat->stmmac_clk. This clock
>    is created by the same code which initialises plat->eee_usecs_rate,
>    which is also created to run at this same rate. Since Marek's
>    commit, this will set this register appropriately using the
>    rate of this clock.
> 
> Therefore, dwmac-intel.c writing GMAC_1US_TIC_COUNTER serves no
> useful purpose and can be removed.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew