netdev - Re: [PATCH v2 5/5] ARM: dts: ls1021a-tsn: Use the DSPI controller in poll mode

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Message-ID: <20190911063350.GB17142@dragon>
Date:   Wed, 11 Sep 2019 14:33:51 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>, devicetree@...r.kernel.org,
        netdev <netdev@...r.kernel.org>, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v2 5/5] ARM: dts: ls1021a-tsn: Use the DSPI controller in
 poll mode

On Tue, Aug 27, 2019 at 09:16:39PM +0300, Vladimir Oltean wrote:
> On Tue, 27 Aug 2019 at 21:13, Mark Brown <broonie@...nel.org> wrote:
> >
> > On Tue, Aug 27, 2019 at 09:06:14PM +0300, Vladimir Oltean wrote:
> > > On Tue, 27 Aug 2019 at 21:05, Mark Brown <broonie@...nel.org> wrote:
> > > > On Mon, Aug 26, 2019 at 04:10:51PM +0300, Vladimir Oltean wrote:
> >
> > > > > I noticed you skipped applying this patch, and I'm not sure that Shawn
> > > > > will review it/take it.
> > > > > Do you have a better suggestion how I can achieve putting the DSPI
> > > > > driver in poll mode for this board? A Kconfig option maybe?
> >
> > > > DT changes go through the relevant platform trees, not the
> > > > subsystem trees, so it's not something I'd expect to apply.
> >
> > > But at least is it something that you expect to see done through a
> > > device tree change?
> >
> > Well, it's not ideal - if it performs better all the time the
> > driver should probably just do it unconditionally.  If there's
> > some threashold where it tends to perform better then the driver
> > should check for that but IIRC it sounds like the interrupt just
> > isn't at all helpful here.
> 
> I can't seem to find any situation where it performs worse. Hence my
> question on whether it's a better idea to condition this behavior on a
> Kconfig option rather than a DT blob which may or may not be in sync.

DT is a description of hardware not condition for software behavior,
where module parameter is usually used for.

Shawn