On Tue, Dec 07, 2021 at 08:15:24PM +0100, Andrew Lunn wrote:

quoted

The qca tag header provide a TYPE value that refer to a big list of
Frame type. In all of this at value 2 we have the type that tells us
that is a READ_WRITE_REG_ACK (aka a mdio rw Ethernet packet)

The idea of using the tagger is to skip parsing the packet 2 times
considering the qca tag header is present at the same place in both
normal packet and mdio rw Ethernet packet.

Your idea would be hook this before the tagger and parse it?
I assume that is the only way if this has to be generilized. But I
wonder if this would create some overhead by the double parsing.

So it seems i remembered this incorrectly. Marvell call this Remote
Management Unit, RMU. And RMU makes use of bits inside the Marvell
Tag. I was thinking it was outside of the tag.

So, yes, the tagger does need to be involved in this.

The initial design of DSA was that the tagger and main driver were
kept separate. This has been causing us problems recently, we have use
cases where we need to share information between the tagger and the
driver. This looks like it is going to be another case of that.

	Andrew

I mean if you check the code this is still somewhat ""separate"".
I ""abuse"" the dsa port priv to share the required data.
(I allocate a different struct... i put it in qca8k_priv and i set every
port priv to this struct)

Wonder if we can add something to share data between the driver and the
port so the access that from the tagger. (something that doesn't use the
port priv)

-- 
	Ansuel