Re: [PATCH v3 2/3] net: ethernet: actions: Add Actions Semi Owl Ethernet MAC driver

Hi Amit,

On Mon, Jun 28, 2021 at 01:55:40PM +0530, Amit Tomer wrote:

Hi,

quoted

quoted

Do you know the story behind this Ethernet controller?

I just happened to get a board based on the S500 SoC, so I took this
opportunity to help improving the mainline kernel support, but other
than that I do not really know much about the hardware history.

quoted

The various
receive/transmit descriptor definitions are 99% those defined in
drivers/net/ethernet/stmmicro/stmmac/descs.h for the normal descriptor.

That's an interesting observation. I could only assume the vendor did
not want to reinvent the wheel here, but I cannot say if this is a
common design scheme or is something specific to STMicroelectronics
only.

I am not entirely sure about it but it looks like it *may* only need
to have a glue driver to
connect to DWMAC.

From the RX/TX descriptors perspective, this looks like a Synopsys IP,
but the MAC register layout is not similar at all.

Thanks to Mani, a request for clarification has been also sent to Actions,
but they could not confirm. Hence, at the moment, we do not have clear
evidences that it is based on Designware.

For instance, on the U-boot[1] side (S700 is one of 64bit OWL SoC from
actions), we kind of re-uses already
existing DWMAC and provide a glue code, and on the Linux side as well
have some similar implementation (locally).

The S700 SoC provides Gigabit ethernet capabilities and I assume the
controller is quite different from the 10/100 variant present on S500.
As a matter of fact, Actions has confirmed that in the case of S700, the
licensing was obtained from a third party IP company, although they were
not certain if the provider had previous agreements with Synopsys.

Regards,
Cristi

Thanks
-Amit.

[1]: https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/net/dwmac_s700.c

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel