RE: [PATCH] net/ixgbe: Treat 1G Cu SFPs as 1G SX on the X550 devices

[Jeff Daly <jeffd@silicom-usa.com>]

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Thursday, April 14, 2022 8:19 AM
> To: Wang, Haiyue <haiyue.wang@intel.com>
> Cc: Jeff Daly <jeffd@silicom-usa.com>; dev@dpdk.org; Stephen Douthit
> <stephend@silicom-usa.com>; qi.z.zhang@intel.com;
> john.mcnamara@intel.com
> Subject: Re: [PATCH] net/ixgbe: Treat 1G Cu SFPs as 1G SX on the X550
> devices
> 
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> 
> 14/04/2022 14:13, Wang, Haiyue:
> > From: Thomas Monjalon <thomas@monjalon.net>
> > > 14/04/2022 03:31, Wang, Haiyue:
> > > > From: jeffd@silicom-usa.com <jeffd@silicom-usa.com>
> > > > > From: Stephen Douthit <stephend@silicom-usa.com>
> > > > >
> > > > > 1G Cu SFPs are not officially supported on the X552/X553 family
> > > > > of devices but treat them as 1G SX modules since they usually
> > > > > work.  Print a warning though since support isn't validated,
> > > > > similar to what already happens for other unofficially supported
> > > > > SFPs enabled via the allow_unsupported_sfps parameter inherited
> from the mainline Linux driver.
> > > > >
> > > > > Signed-off-by: Stephen Douthit <stephend@silicom-usa.com>
> > > > > Signed-off-by: Jeff Daly <jeffd@silicom-usa.com>
> > > > > ---
> > > > >  drivers/net/ixgbe/base/ixgbe_x550.c | 14 +++++++++++++-
> > > > >  1 file changed, 13 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/net/ixgbe/base/ixgbe_x550.c
> > > > > b/drivers/net/ixgbe/base/ixgbe_x550.c
> > > > > index 8810d1658e..8d1bc6c80d 100644
> > > > > --- a/drivers/net/ixgbe/base/ixgbe_x550.c
> > > > > +++ b/drivers/net/ixgbe/base/ixgbe_x550.c
> > > > > @@ -1538,9 +1538,21 @@ STATIC s32
> > > > > ixgbe_supported_sfp_modules_X550em(struct ixgbe_hw *hw, bool
> > > *linear)
> > > >
> > > > NACK.
> > > >
> > > > As for 1G Cu SFP treating it as 1G SX, some 1G-Base-T SFP modules
> > > > require the use of RX_ILOS and some Intel Ethernet products don't
> support that.
> > >
> > > So what is the solution?
> > >
> > > > And the DPDK keeps the same design with kernel.
> > >
> > > It should not be a justification for limiting DPDK features.
> >
> > Um, this is upstream version driver to keep the same behavior.
> >
> > There are also some kind of custom release ...
> 
> I don't understand.
> Upstream DPDK (and Linux) must support a maximum of hardware and
> setup.
> Why rejecting adding such compatibility?
> 

so, I will ask a question directly in case people just aren't inclined to make a suggestion
(and perhaps this should be also directed to the Linux kernel driver mailing list), but
if there's a driver option: module_param(allow_unsupported_sfp, uint, 0) to allow 
enabling non-official support of some SFPs, then I can't image that it wouldn't also be
acceptable to add: module_param(cu_sfp_as sx, uint, 0) to be able to select whether
to enable this specific handling as well?

if a patch of this nature is acceptable to Linux driver maintainers, then it would also be
here as well according to your explanation of the NACK,  correct?