netdev - Re: [PATCH net-next 0/2] mlxsw: Add support for QSFP-DD transceiver type

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Message-ID: <CAL_jBfRojYBvkD5fW_gLAxWiLaiSD7mQ_rXGjSaDxnkdK3gCiA@mail.gmail.com>
Date:   Fri, 26 Jun 2020 17:45:51 +0100
From:   Adrian Pop <popadrian1996@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Ido Schimmel <idosch@...sch.org>, netdev@...r.kernel.org,
        davem@...emloft.net, kuba@...nel.org, jiri@...lanox.com,
        vadimp@...lanox.com, mlxsw@...lanox.com,
        Ido Schimmel <idosch@...lanox.com>
Subject: Re: [PATCH net-next 0/2] mlxsw: Add support for QSFP-DD transceiver type

Hi Ido, Andrew!

I'm happy to receive these emails and to see that my old patch had
some interest. Yes, at that time there was no official support for
QSFP-DD in the upstream kernel. I was able to test my code using a
custom driver we developed in my company. If everything works out, I'd
be happy to re-submit it.

> It is a while ago, but i thought there was something odd about the
> order of the pages, or the number of the pages? And there was no clear
> indication from the kernel about QSPF page format vs QSPF-DD page
> format?
>
> So Adrian's patch is probably a good starting point, but i think it
> needs further work.

It is true, my patch was basically defining a KAPI. The decision to
have the pages 0x10 and 0x11 right after 0x00, 0x01 and 0x02 was made
based on the need to provide the same stats for QSFP-DD as for QSFP.
At that point, page 0x03 was not needed. Anyway, due to the way I
defined the offset values in qsfp-dd.h, if we add page 0x03 it would
be extremely easy to just change

#define PAG11H_OFFSET (0x04 * 0x80)
to
#define PAG11H_OFFSET (0x05 * 0x80)

and probably everything else would stay the same.
We can continue our discussion about the needed pages in the "[PATCH
net-next 1/2]" e-mails chain.


On Fri, 26 Jun 2020 at 16:06, Andrew Lunn <andrew@...n.ch> wrote:
>
> On Fri, Jun 26, 2020 at 05:53:42PM +0300, Ido Schimmel wrote:
> > On Fri, Jun 26, 2020 at 05:47:22PM +0300, Ido Schimmel wrote:
> > > From: Ido Schimmel <idosch@...lanox.com>
> > >
> > > This patch set from Vadim adds support for Quad Small Form Factor
> > > Pluggable Double Density (QSFP-DD) modules in mlxsw.
> >
> > Adrian,
> >
> > In November you sent a patch that adds QSFP-DD support in ethtool user
> > space utility:
> > https://patchwork.ozlabs.org/project/netdev/patch/20191109124205.11273-1-popadrian1996@gmail.com/
> >
> > Back then Andrew rightfully noted that no driver in the upstream kernel
> > supports QSFP-DD and the patch was deferred.
>
> Hi Ido
>
> It is a while ago, but i thought there was something odd about the
> order of the pages, or the number of the pages? And there was no clear
> indication from the kernel about QSPF page format vs QSPF-DD page
> format?
>
> So Adrian's patch is probably a good starting point, but i think it
> needs further work.
>
>       Andrew