RE: [PATCH V1 net-next 0/3] net: stmmac: implement clocks

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: 2021年2月24日 21:02
To: Jakub Kicinski <kuba@kernel.org>
Cc: Joakim Zhang <redacted>; peppe.cavallaro@st.com;
alexandre.torgue@st.com; joabreu@synopsys.com; davem@davemloft.net;
netdev@vger.kernel.org; dl-linux-imx [off-list ref]
Subject: Re: [PATCH V1 net-next 0/3] net: stmmac: implement clocks

quoted

Understood. Please double check ethtool callbacks work fine. People
often forget about those when disabling clocks in .close.

The MDIO bus can also be used at any time, not just when the interface is open.
For example the MAC could be connected to an Ethernet switch, which is
managed by the MDIO bus. Or some PHYs have a temperature sensor which is
registered with HWMON when the PHY is probed.

Hi Andrew,

I don't have experience with Ethernet switch, according to your points, you mean we can connect STMMAC to an Ethernet switch, and then Ethernet switch managed STMMAC by the MDIO bus but without checking whether STMMAC interface is opened or not, so STMMAC needs clocks for MDIO even interface is closed, right?

You said you copied the FEC driver. Take a look at that, it was initially broken in
this way, and i needed to extend it when i got a board with an Ethernet switch
attached to the FEC.

Could you point me how to implement clocks management to cover above Ethernet switch case? Or can we upstream this first and then fix it later for such case?

Best Regards,
Joakim Zhang

      Andrew