Hi Andrew,

On Mon, 27 Jan 2020 at 18:04, Andrew Lunn [off-list ref] wrote:

quoted

Is this sufficient?
I suppose this works because you have flow control enabled by default?
What would happen if the user would disable flow control with ethtool?

It will still work. Network protocols expect packets to be dropped,
there are bottlenecks on the network, and those bottlenecks change
dynamically. TCP will still be able to determine how much traffic it
can send without too much packet loss, independent of if the
bottleneck is here between the MAC and the PHY, or later when it hits
an RFC 1149 link.

Following this logic, this patch isn't needed at all, right? The PHY
will drop frames that it can't hold in its small FIFOs when adapting a
link speed to another, and higher-level protocols will cope. And flow
control at large isn't needed.

What I was trying to see Madalin's opinion on was whether in fact we
want to keep the RX flow control as 'fixed on' if the MAC supports it
and the PHY needs it, _as a function of the current phy_mode and maybe
link speed_ (the underlined part is important IMO).

    Andrew

Thanks,
-Vladimir