linux-kernel - Re: [PATCH 2/3] arm: tegra: enable igb, stmpe, i2c chardev, spidev, lm95245, pwm leds

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Date:	Tue, 10 Jun 2014 00:16:13 +0200
From:	Marcel Ziswiler <marcel@...wiler.com>
To:	Mark Brown <broonie@...nel.org>
CC:	Stephen Warren <swarren@...dotorg.org>, thierry.reding@...il.com,
	linux@....linux.org.uk, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org, stefan@...er.ch
Subject: Re: [PATCH 2/3] arm: tegra: enable igb, stmpe, i2c chardev, spidev,
 lm95245, pwm leds

On 06/04/2014 01:17 PM, Mark Brown wrote:
> You're saying you're controlling it from userspace.  This is a
> particular detail of what you are doing in your system.  You happen to
> want to control the devices you are hanging off the system with
> userspace drivers but that's just what you're doing right now.

Sorry, I don't get it. Yes, spidev is to control stuff from user space 
just like i2c-dev however bad that might sound.

> No, that's in the controller node - the chip selects are described
> there.  The child node references a chip select number that the master
> has and describes what's connected to that chip select.

Well, unfortunately SPI without any chip select is just plain simply 
useless. It won't work.

> It's a perfectly fine way of controlling things from userspace if that's
> a sensible way of controlling devices but that does not mean you should
> describe it in the device tree in that fashion.

Only that without describing such a chip select in the device tree 
spidev won't ever work.

I don't see us reaching any consensus here therefore I retreat. I will 
re-submit the whole thing without spidev however sad having to see that 
useful feature being dropped.
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