Date: Wed, 13 May 2015 08:37:40 -0700
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Mark Brown <broonie@kernel.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>,
        linux-kernel@vger.kernel.org, Hans de Goede <hdegoede@redhat.com>,
        linux-spi@vger.kernel.org, Martin Sperl <kernel@martin.sperl.org>,
        Michal Suchanek <hramrach@gmail.com>
Subject: Re: [PATCH] spi: Force the registration of the spidev devices
Message-ID: <20150513153740.GC11677@kroah.com>
References: <1431462804-30467-1-git-send-email-maxime.ripard@free-electrons.com>
 <20150513112604.GI3066@sirena.org.uk>
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On Wed, May 13, 2015 at 12:26:04PM +0100, Mark Brown wrote:
> On Tue, May 12, 2015 at 10:33:24PM +0200, Maxime Ripard wrote:
> 
> > While this is nicer than the DT solution because of its accurate hardware
> > representation, it's still not perfect because you might not have access to the
> > DT, or you might be driving a completely generic device (such as a
> > microcontroller) that might be used for something else in a different
> > context/board.
> 
> Greg, you're copied on this because this seems to be a generic problem
> that should perhaps be solved at a driver model level - having a way to
> bind userspace access to devices that we don't otherwise have a driver
> for.  The subsystem could specify the UIO driver to use when no other
> driver is available.

That doesn't really work.  I've been talking to the ACPI people about
this, and the problem is "don't otherwise have a driver for" is an
impossible thing to prove, as you never know when a driver is going to
be loaded from userspace.

You can easily bind drivers to devices today from userspace, why not
just use the built-in functionality you have today if you "know" that
there is no driver for this hardware.

thanks,

greg k-h
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