Re: [RFC RESEND v1 pinctrl-next 0/1] add blink and activity functions to SGPIO

Hi Andrew and Christian,

On Wed, Jul 12, 2023 at 04:55:44PM +0200, Andrew Lunn wrote:

On Wed, Jul 12, 2023 at 03:59:10AM +0200, Christian Marangi wrote:

quoted

On Tue, Jul 11, 2023 at 07:22:49PM -0700, Colin Foster wrote:

quoted

Preface (new for resend):

This is a resend of a patch I'd sent a couple years back. At that time,
I was told to wait for hardware-offloaded LEDS. It looks like that time
has finally come, so I've changed this from PATCH down to an RFC to make
sure this is the right approach for the framework.

Ocelot chips (VSC7511, VSC7512, VSC7513, VSC7514) have support for
hardware-offloaded LEDs based on network activity. This is currenty
managed by way of pinctrl-microchip-sgpio (and this current patch).

The purpose of this resend is two-fold. First, to come up with an idea
of how this pinctrl-microchip-sgpio module can fit in with the new
hardware-offloaded netdev triggers Christian Marangi recently added. Is
this something that should be in the pinctrl module itself? Or should
there be a drivers/net/ethernet/mscc/ocelot_leds.c module that I should
add?

I'm a bit out of the loop on what magic OEM did to make LED work on
ocelot but I feel an ocelot_leds submodule is needed.

The configuration is basically SPI to an GPIO expander. The ocelot chip
fully manages the SPI bus.

quoted

To correctly supports the hw many API needs to be defined and for switch
I would stick with how things are done with qca8k, codewise and DT wise
(with how LEDs are defined in DT)

Ideally the feature for MAC will be generilized and added to the DSA ops
struct, so having things in the DSA driver would make the migration
easier.

`ocelot` is a bit of an odd device, since it is both a DSA device for
felix and seville and a pure switchdev device for ocelot.

Now you tell me :-)

You need some integration with the switch driver, because i expect
only the switch driver has the knowledge of how LEDs are mapped to
struct netdev and ports. And in order to offload blinking you need
that mapping.

I have some WIP patches to add a generalized DSA interface for LEDs,
and support for mv88e6xxx. I would also like to move qca8k over to
that. So it could be that felix and seville would use that. Ocelot
would need to do it slightly different, but i expect it is just a
layer on top of some shared code, much like the rest of ocelot.

Based on this comment, I might sit on the sidelines for a couple more
cycles.

Having pinmux in the middle is interesting. I've no idea how that will
work, but i've not looked at it.

Yeah, I'm not exactly sure either. And integration with the switch
driver will be interesting to say the least. I don't know if Felix /
Seville have this capability (probably not).


I'll keep all this on the back of my mind. It seems like there will
definitely be some subtleties in any way. I figure it is better to bring
up the concept earlier than later, so thanks for the feedback!

      Andrew