On Wed, Jan 20, 2021 at 03:41:58PM -0800, Jakub Kicinski wrote:

On Wed, 20 Jan 2021 14:56:46 +0100 Andrew Lunn wrote:

quoted

quoted

No, the FW does not know. The ASIC is not physically able to get the
linecard type. Yes, it is odd, I agree. The linecard type is known to
the driver which operates on i2c. This driver takes care of power
management of the linecard, among other tasks.  

So what does activated actually mean for your hardware? It seems to
mean something like: Some random card has been plugged in, we have no
idea what, but it has power, and we have enabled the MACs as
provisioned, which if you are lucky might match the hardware?

The foundations of this feature seems dubious.

But Jiri also says "The linecard type is known to the driver which
operates on i2c." which sounds like there is some i2c driver (in user
space?) which talks to the card and _does_ have the info? Maybe I'm
misreading it. What's the i2c driver?

Hi Jakub

A complete guess, but i think it will be the BMC, not the ASIC. There
have been patches from Mellanox in the past for a BMC, i think sent to
arm-soc, for the ASPEED devices often used as BMCs. And the BMC is
often the device doing power management. So what might be missing is
an interface between the driver and the BMC. But that then makes the
driver system specific. A OEM who buys ASICs and makes their own board
could have their own BMC running there own BMC firmware.

All speculation...

      Andrew