linux-kernel - Re: [linux-sunxi] [PATCH 2/3] spidev: Add DT binding example.

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Date:	Mon, 27 Apr 2015 12:05:37 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Michal Suchanek <hramrach@...il.com>
Cc:	Hans de Goede <hdegoede@...hat.com>,
	Martin Sperl <kernel@...tin.sperl.org>,
	Mark Brown <broonie@...nel.org>,
	linux-sunxi <linux-sunxi@...glegroups.com>,
	Jonathan Corbet <corbet@....net>,
	linux-spi <linux-spi@...r.kernel.org>,
	linux-doc <linux-doc@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [linux-sunxi] [PATCH 2/3] spidev: Add DT binding example.

On Mon, Apr 27, 2015 at 08:51:12AM +0200, Michal Suchanek wrote:
> On 26 April 2015 at 17:47, Maxime Ripard
> <maxime.ripard@...e-electrons.com> wrote:
> > On Sun, Apr 26, 2015 at 04:40:50PM +0200, Hans de Goede wrote:
> >> Hi,
> >>
> >> I've a feeling everyone in this thread is ignoring the
> >> raspberry pi use-case. Where the board is specifically
> >> designed for educational purposes and used with lots of
> >> peripherals which are usually programmed from userspace
> >> using e.g. python bindings for i2c-dev or spidev, for
> >> such a setup we really want spidev to be loaded on the
> >> spibus by default and we really do not have a proper
> >> compatible for a child device.
> >
> > I'm not sure we're ignoring it, it just is the exact same use case
> > than the whole spidev use case: people want to write SPI userspace
> > drivers, the rpi really is not special here, except maybe for its user
> > space code base, but it really boils down to the same issue.
> >
> >> And no having to use per device devicetree overlays
> >> for this is not the answer, this needs to be really
> >> really easy. With pre device-tree kernels this just
> >> works, we should be able to match that ease of use
> >> with devicetree.
> >
> > We do agree on that. We repeatedly told that the DT was not a good
> > solution, overlays or not, and this is exactly one of the reasons.
> >
> 
> Ok, so how about skipping the bindings altogether.
> 
> Just instantiate a spidev for each SPI bus and each CS the SPI core
> knows of once spidev is loaded.

Which is exactly what my patch did but didn't seem like good enough
for you at the time...

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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