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

-----Original Message-----
From: Russell King <linux@armlinux.org.uk>
Sent: Monday, 17 May, 2021 6:54 PM
To: Sit, Michael Wei Hong <redacted>
Cc: Jose.Abreu@synopsys.com; andrew@lunn.ch;
hkallweit1@gmail.com; kuba@kernel.org;
netdev@vger.kernel.org; peppe.cavallaro@st.com;
alexandre.torgue@foss.st.com; davem@davemloft.net;
mcoquelin.stm32@gmail.com; Voon, Weifeng
[off-list ref]; Ong, Boon Leong
[off-list ref]; Tan, Tee Min
[off-list ref]; vee.khee.wong@linux.intel.com;
Wong, Vee Khee [off-list ref]; linux-stm32@st-
md-mailman.stormreply.com; linux-arm-
kernel@lists.infradead.org; linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 2/2] net: stmmac: Add callbacks for
DWC xpcs Energy Efficient Ethernet

On Mon, May 17, 2021 at 05:43:32PM +0800, Michael Sit Wei Hong
wrote:

quoted

Link xpcs callback functions for MAC to configure the xpcs EEE

feature.

quoted

The clk_eee frequency is used to calculate the

MULT_FACT_100NS. This

quoted

is to adjust the clock tic closer to 100ns.

Signed-off-by: Michael Sit Wei Hong

[off-list ref]

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.

--
RMK's Patch system:
https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at
last!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel