Re: [PATCH] ethtool: Add QSFP-DD support

[Andrew Lunn <andrew@lunn.ch>]

On Fri, Jul 31, 2020 at 11:47:25AM +0300, Adrian Pop wrote:
> The Common Management Interface Specification (CMIS) for QSFP-DD shares
> some similarities with other form factors such as QSFP or SFP, but due to
> the fact that the module memory map is different, the current ethtool
> version is not able to provide relevant information about an interface.
> 
> This patch adds QSFP-DD support to ethtool. The changes are similar to
> the ones already existing in qsfp.c, but customized to use the memory
> addresses and logic as defined in the specifications document.
> 
> Page 0x00 (lower and higher memory) are always implemented, so the ethtool
> expects at least 256 bytes if the identifier matches the one for QSFP-DD.
> For optical connected cables, additional pages are usually available (the
> contain module defined  thresholds or lane diagnostic information). In
> this case, ethtool expects to receive 768 bytes in the following format:
> 
>     +----------+----------+----------+----------+----------+----------+
>     |   Page   |   Page   |   Page   |   Page   |   Page   |   Page   |
>     |   0x00   |   0x00   |   0x01   |   0x02   |   0x10   |   0x11   |
>     |  (lower) | (higher) | (higher) | (higher) | (higher) | (higher) |
>     |   128B   |   128B   |   128B   |   128B   |   128B   |   128B   |
>     +----------+----------+----------+----------+----------+----------

Hi Adrian

Didn't we discuss that page 3 might be useful? I would prefer not to
document that pages 0x10 and 0x11 would follow page 2 until we have a
driver which does actually provide pages 0x10 and 0x11.

       Andrew