Re: [PATCH net-next 2/2] net: stmmac: Add callbacks for DWC xpcs Energy Efficient Ethernet

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: "Sit, Michael Wei Hong" <michael.wei.hong.sit@intel.com>
Cc: "Jose.Abreu@synopsys.com" <Jose.Abreu@synopsys.com>,
	"andrew@lunn.ch" <andrew@lunn.ch>,
	"hkallweit1@gmail.com" <hkallweit1@gmail.com>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"peppe.cavallaro@st.com" <peppe.cavallaro@st.com>,
	"alexandre.torgue@foss.st.com" <alexandre.torgue@foss.st.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"mcoquelin.stm32@gmail.com" <mcoquelin.stm32@gmail.com>,
	"Voon, Weifeng" <weifeng.voon@intel.com>,
	"Ong, Boon Leong" <boon.leong.ong@intel.com>,
	"Tan, Tee Min" <tee.min.tan@intel.com>,
	"vee.khee.wong@linux.intel.com" <vee.khee.wong@linux.intel.com>,
	"Wong, Vee Khee" <vee.khee.wong@intel.com>,
	"linux-stm32@st-md-mailman.stormreply.com"
	<linux-stm32@st-md-mailman.stormreply.com>,
	 "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next 2/2] net: stmmac: Add callbacks for DWC xpcs Energy Efficient Ethernet
Date: Tue, 18 May 2021 11:06:27 +0100	[thread overview]
Message-ID: <20210518100627.GT12395@shell.armlinux.org.uk> (raw)
In-Reply-To: <CO1PR11MB50447EDBEB4835C3EB5B3C7A9D2D9@CO1PR11MB5044.namprd11.prod.outlook.com>

On Mon, May 17, 2021 at 11:37:12AM +0000, Sit, Michael Wei Hong wrote:
> > From: Russell King <linux@armlinux.org.uk>
> > 
> > On Mon, May 17, 2021 at 05:43:32PM +0800, Michael Sit Wei Hong
> > wrote:
> > > Link xpcs callback functions for MAC to configure the xpcs EEE
> > feature.
> > >
> > > The clk_eee frequency is used to calculate the
> > MULT_FACT_100NS. This
> > > is to adjust the clock tic closer to 100ns.
> > >
> > > Signed-off-by: Michael Sit Wei Hong
> > <michael.wei.hong.sit@intel.com>
> > 
> > What is the initial state of the EEE configuration before the first
> > call to stmmac_ethtool_op_set_eee()? Does it reflect the default
> > EEE settings?
> 
> The register values before the first call are the default reset values in
> the registers. The reset values assumes the clk_eee_i time period is 10ns,
> Hence, the reset value is set to 9.
> According to the register description,
> This value should be programmed such that the
> clk_eee_i_time_period * (MULT_FACT_100NS + 1) should be
> within 80 ns to 120 ns.
> 
> Since we are using a fixed 19.2MHz clk_eee, which is 52ns,
> we are setting the value to 1.

Does that hardware default configuration match what is returned by
ethtool --show-eee ?

-- 
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