From: andrew@lunn.ch (Andrew Lunn)
Date: Fri, 4 Jul 2014 16:15:41 +0200
Subject: [PATCH 2/8] cpufreq: add driver for Armada XP
In-Reply-To: <1404481934.4634.2.camel@weser.hi.pengutronix.de>
References: <1404467103-29644-1-git-send-email-thomas.petazzoni@free-electrons.com>
 <1404467103-29644-3-git-send-email-thomas.petazzoni@free-electrons.com>
 <CAKohponuvPd1kWDdB66kxd8TxxYqQ219jCq2D2RGhMHAuZTSWA@mail.gmail.com>
 <20140704131247.2c8ecde2@free-electrons.com>
 <1404481934.4634.2.camel@weser.hi.pengutronix.de>
Message-ID: <20140704141541.GE7773@lunn.ch>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, Jul 04, 2014 at 03:52:14PM +0200, Lucas Stach wrote:
> Am Freitag, den 04.07.2014, 13:12 +0200 schrieb Thomas Petazzoni:
> [...]
> > This doesn't work very well with the idea of having the OPP table
> > statically encoded in to the Device Tree. Options are:
> > 
> >  - Improve the cpufreq-cpu0 driver so that the OPP table can be passed
> >    through platform_data, and therefore built dynamically by the
> >    platform code and passed when registering the cpufreq
> >    platform_device.
> > 
> >  - Dynamically build/update the OPP table in the Device Tree.
> 
> This sounds like the right thing to do. Ideally your bootloader would do
> this for you, so you don't have to encode those properties statically at
> all.
> 
> Barebox already has facilities to fixup any loaded device tree. Have a
> look at of_register_fixup() there.

We are talking about legacy devices here, which have been in the field
for years. There is very little chance of a boot loader
upgrade. Appended DT is the norm for these devices, and modifying the
DT would have to happen in kernel.

   Andrew