[LEDE-DEV] clarifying how trivial it is to define a couple new IMX6QDL targets

[Robert P. J. Day]

On Fri, 29 Sep 2017, Florian Fainelli wrote:

> On 09/29/2017 10:33 AM, Robert P. J. Day wrote:
> >
> >   i was just looking at using latest LEDE to define a couple new
> > IMX6QDL targets, and after a few minutes, it looks as if, at least
> > to get a minimal bootable system and as long as i'm not doing
> > anything drastically weird, it should be wickedly simple and i
> > just want to verify that.
> >
> >   it's all based on the fact that, with the current kernel, the
> > only selection you need to make is CONFIG_SOC_IMX6Q, which will
> > build a suitable kernel, whereupon the file
> > arch/arm/boot/dts/Makefile contains the directive:
> >
> >     dtb-$(CONFIG_SOC_IMX6Q) += \
> >        ... over 100 target dtb files ...
> >
> >   under the circumstances, given that that single kernel is
> > compatible with that many targets, it would appear that, as long
> > as i don't care that 100+ other dtb files will be compiled, i can
> > just add, under the LEDE directory
> > target/linux/imx6/files-4.9/arch/arm/boot/dts, a couple new .dts
> > files, like:
> >
> >   acme_coyote_1.dts
> >   acme_coyote_2.dts
> >
> > and that's it.
> >
> >   of course, there might be enhancements down the road but, for
> > now, just to get something bootable, it seems all i need to do is
> > patch a couple entries into arch/arm/boot/dts/Makefile, and add
> > the dts files.
> >
> >   am i understanding this correctly?
>
> As far as the kernel and DTS build is concerned that is pretty much
> all that is needed, you will need a patch to
> arch/arm/boot/dts/Makefile to make sure that your DTS get built into
> a DTB AFAICT.

  right ... so all under target/linux/imx6/, i would do two things:

1) patch arch/arm/boot/dts/Makefile to add my new .dtb files to be
built when CONFIG_SOC_IMX6Q (thereby building 105 .dtb files, not just
the current 103 :-)

2) throw a couple new .dts files under
files-4.9/arch/arch/arm/boot/dts

> You will probably need to pair the DTS file(s) with an appropriate
> change under target/linux/imx6/image/Makefile that adds a new
> Device/acme-coyote1 and has at least a DEVICE_DTS :=
> acme_coyote_1.dts to build a kernel with an appended DTB image.

  i was in fact wondering about that ... i can see the definition of a
couple Ventana boards in that image/Makefile, and it may well become
necessary to add entries for my new boards there at some point
depending on customization. but if all i'm after right this minute is
a generic kernel paired with my new .dtb files, i don't actually need
to define my devices in that Makefile, do i? this is assuming that the
generic build will give me just enough to boot, and i can worry about
customization later.

  sound reasonable?

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
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