netdev - RE: [PATCH 1/2] net/fsl: fman: Allow fm_max_frame_sz & rx_extra

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Message-ID: <AM6PR04MB397692A930803C5CB6B1D568EC379@AM6PR04MB3976.eurprd04.prod.outlook.com>
Date:   Fri, 18 Feb 2022 11:33:43 +0000
From:   Madalin Bucur <madalin.bucur@....com>
To:     EVS Hardware Dpt <hardware.evs@...il.com>
CC:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2] net/fsl: fman: Allow fm_max_frame_sz &
 rx_extra_headroom config from devicetree.

> -----Original Message-----
> From: EVS Hardware Dpt <hardware.evs@...il.com>
> Subject: Re: [PATCH 1/2] net/fsl: fman: Allow fm_max_frame_sz &
> rx_extra_headroom config from devicetree.
> 
> Hi Madalin, Guys
> 
> I know, but it's somewhat difficult to use those parameters on kernel's
> command line.
> I don't think it's wrong to also add that in devicetree.
> No removal, just an added feature.
> 
> For ethernet node in devicetree, there are a lot of configuration stuff
> like
> max-frame-size to allow configuration of MTU
> (and so potentially enable jumbo) and it's regarded as fine.
> 
> It's also the goal of this patch. Allow an easy configuration of
> fsl_fm_max_frm from a dts. I added rx_extra_headroom for the sake of
> completeness.
> 
> So I plead for this addition because I don't think it's wrong to do that
> and
> I consider it's nicer to add an optional devicetree property rather than
> adding a lot of obscure stuff on kernel's command line.
> 
> Hope you'll share my point of view.
> 
> Have a nice weekend Madalin, Guys,
> Fred.

Hi, Fred,

I understand your concerns in regards to usability but the device trees, as
explained earlier by Jakub, have a different role - they describe the HW,
rather than configure the SW on it. Removal of such config entries from the
device tree was one item on a long list to get the DPAA drivers upstreamed.

> Le ven. 18 févr. 2022 à 08:23, Madalin Bucur <madalin.bucur@....com> a
> écrit :
> >
> > > -----Original Message-----
> > > From: Fred Lefranc <hardware.evs@...il.com>
> > > Subject: [PATCH 1/2] net/fsl: fman: Allow fm_max_frame_sz &
> > > rx_extra_headroom config from devicetree.
> > >
> > > Allow modification of two additional Frame Manager parameters :
> > > - FM Max Frame Size : Can be changed to a value other than 1522
> > >   (ie support Jumbo Frames)
> > > - RX Extra Headroom
> > >
> > > Signed-off-by: Fred Lefranc <hardware.evs@...il.com>
> >
> > Hi, Fred,
> >
> > there are module params already for both, look into
> >
> > drivers/net/ethernet/freescale/fman/fman.c
> >
> > for fsl_fm_rx_extra_headroom and fsl_fm_max_frm.
> >
> > Regards,
> > Madalin