Re: [EXT] Re: [PATCH net-next 0/1] net: fec: add C45 MDIO read/write support

On Tue, Aug 20, 2019 at 02:32:26AM +0000, Andy Duan wrote:

From: Andrew Lunn <andrew@lunn.ch>

quoted

On Mon, Aug 19, 2019 at 05:11:14PM +0000, Marco Hartmann wrote:

quoted

As of yet, the Fast Ethernet Controller (FEC) driver only supports
Clause 22 conform MDIO transactions. IEEE 802.3ae Clause 45 defines a
modified MDIO protocol that uses a two staged access model in order to
increase the address space.

This patch adds support for Clause 45 conform MDIO read and write
operations to the FEC driver.

Hi Marco

Do all versions of the FEC hardware support C45? Or do we need to make use
of the quirk support in this driver to just enable it for some revisions of FEC?

Thanks
        Andrew

i.MX legacy platforms like i.MX6/7 series, they doesn't support Write & Read Increment.
But for i.MX8MQ/MM series, it support C45 full features like Write & Read Increment.

For the patch itself, it doesn't support Write & Read Increment, so I think the patch doesn't
need to add quirk support.

Hi Andy

So what happens with something older than a i.MX8MQ/MM when a C45
transfer is attempted? This patch adds a new write. Does that write
immediately trigger a completion interrupt? Does it never trigger an
interrupt, and we have to wait FEC_MII_TIMEOUT?

Ideally, if the hardware does not support C45, we want it to return
EOPNOTSUPP.

Thanks
	Andrew