RE: [PATCH V2 net-next 2/7] dt-bindings: net: fsl,fec: add RGMII internal clock delay

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: 2021年7月28日 22:08
To: Joakim Zhang <redacted>
Cc: davem@davemloft.net; kuba@kernel.org; robh+dt@kernel.org;
shawnguo@kernel.org; s.hauer@pengutronix.de; kernel@pengutronix.de;
festevam@gmail.com; dl-linux-imx [off-list ref];
netdev@vger.kernel.org; devicetree@vger.kernel.org;
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2 net-next 2/7] dt-bindings: net: fsl,fec: add RGMII
internal clock delay

On Wed, Jul 28, 2021 at 07:51:58PM +0800, Joakim Zhang wrote:

quoted

+      The "enet_2x_txclk"(option), for RGMII sampling clock which fixed at

250Mhz.

quoted

+      The clock is required if SoC RGMII enable clock delay.

Hi Joakim

So you only need the clock if you are using RGMII delays? For RGMII without
delays, the clock is not needed?

You might want to add a check in the C code that the clock is provided when
needed.

Hi Andrew,

Yes, we only need this clock for RGMII delays, the clock is not needed for RGMII without delays.

Had better add below check to avoid enabling needless clock. 
	if (fep->rgmii_txc_dly || fep->rgmii_rxc_dly)

Best Regards,
Joakim Zhang

     Andrew