[Buildroot] [EXT] Re: [PATCH] boot/uboot: add support for custom DT name

[Kostya Porotchkin]

Hi, Thomas,

> -----Original Message-----
> From: buildroot <buildroot-bounces at busybox.net> On Behalf Of Thomas
> Petazzoni
> Sent: Monday, December 24, 2018 15:48
> To: Kostya Porotchkin <kostap at marvell.com>
> Cc: Clemens Gruber <clemens.gruber at pqgruber.com>;
> buildroot at buildroot.org
> Subject: [EXT] Re: [Buildroot] [PATCH] boot/uboot: add support for custom
> DT name
> 
> External Email
> 
> ----------------------------------------------------------------------
> Hello Kostya,
> 
> +Clemens Gruber in Cc, who posted a related U-Boot patch.
> 
> On Mon, 24 Dec 2018 15:19:04 +0200, kostap at marvell.com wrote:
> > From: Konstantin Porotchkin <kostap at marvell.com>
> >
> > Some u-boot default configuration files could be shared between
> > targets and used for building images for multiple board types.
> > The only difference between such builds is the DTB embedded in in the
> > boot image for each specific platform.
> > This approach is widely used by Marvell, having the same u-boot
> > configuration file for the entire SoC family, but allowing builds of
> > multiple target flavors by supplying the device tree name through make
> > command parameter DEVICE_TREE=xxx This patch adds such capability to
> > uboot module of the buildroot.
> > The custome DT name could be  defined by
> > BR2_TARGET_UBOOT_CUSTOM_DTS_NAME entry.
> >
> > Change-Id: I69e193339b0369a736bdf98491b9914d24a54e17
> > Signed-off-by: Konstantin Porotchkin <kostap at marvell.com>
> 
> Reading this again, in fact it is very similar to patch
> http://patchwork.ozlabs.org/patch/881197/ we already have in the queue.
> With a very important distinction: your patch passes DEVICE_TREE=, while
> the existing pending patch passes EXT_DTB=. The obvious question that
> comes up is: which one is right ? Or are these two orthogonal things ?
[KP] As far as I understand, the EXT_DTP is used for pointing to out of the tree pre-compiled DTB file, while DEVICE_TREE allows selection between DTS files existing in u-boot tree. So the first one is for customers that do not want to share their DT details and the second one for re-using the same configuration with different DTs.
Does it makes sense?
Kosta
> 
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
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