Barebox device tree overlay support

Barebox device tree overlay support

[Dgien, David [US] (MS)]

Hello,

When going through the archives it looks like a set of patches were submitted to support device tree overlays in barebox in http://lists.infradead.org/pipermail/barebox/2015-March/022674.html.
But they weren't accepted because overlays weren't fully implemented in the DTC yet.

It looks like overlay support was mainlined in the kernel in 4.11. ( kernel/git/torvalds/linux.git: be5165a51d2500ae1afa1236a8b09858831fdf7e )

Would it be possible to take another look at pulling these patches into the barebox mainline?

Thank you,
David Dgien


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Re: Barebox device tree overlay support

[Sascha Hauer]

Hi David,

On Thu, Jan 11, 2018 at 03:40:49PM +0000, Dgien, David [US] (MS) wrote:
> Hello,
> 
> When going through the archives it looks like a set of patches were submitted to support device tree overlays in barebox in http://lists.infradead.org/pipermail/barebox/2015-March/022674.html.
> But they weren't accepted because overlays weren't fully implemented in the DTC yet.
> 
> It looks like overlay support was mainlined in the kernel in 4.11. ( kernel/git/torvalds/linux.git: be5165a51d2500ae1afa1236a8b09858831fdf7e )

I am still not sure which parts got merged and which are still pending.
There are still overlay patches floating around.

> 
> Would it be possible to take another look at pulling these patches into the barebox mainline?

Generally yes. If you like, please rebase test and respin the patches.

We gave up at that time because we didn't see any good usecase for
overlay support which we can't solve with the instruments we already
have. So I would be glad to hear about your motivation using overlays.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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Re: Barebox device tree overlay support

[Maxime Ripard]

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Hi,

On Fri, Jan 12, 2018 at 08:42:26AM +0100, Sascha Hauer wrote:
> On Thu, Jan 11, 2018 at 03:40:49PM +0000, Dgien, David [US] (MS) wrote:
> > Hello,
> > 
> > When going through the archives it looks like a set of patches
> > were submitted to support device tree overlays in barebox in
> > http://lists.infradead.org/pipermail/barebox/2015-March/022674.html.
> > But they weren't accepted because overlays weren't fully
> > implemented in the DTC yet.
> > 
> > It looks like overlay support was mainlined in the kernel in
> > 4.11. ( kernel/git/torvalds/linux.git:
> > be5165a51d2500ae1afa1236a8b09858831fdf7e )
> 
> I am still not sure which parts got merged and which are still pending.
> There are still overlay patches floating around.

The only thing that's missing in the kernel at the moment is a
user-space interface to load overlays, but the rest has been there for
quite some time.

> > Would it be possible to take another look at pulling these patches
> > into the barebox mainline?
> 
> Generally yes. If you like, please rebase test and respin the patches.

The libfdt gained support to apply overlays quite some time ago
already, so this should be as easy as updating it to a recent enough
version, and creating a wrapper around fdt_apply. This is what U-Boot
is doing.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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Re: Barebox device tree overlay support

[Sascha Hauer]

On Fri, Jan 12, 2018 at 11:11:32AM +0100, Maxime Ripard wrote:
> Hi,
> 
> On Fri, Jan 12, 2018 at 08:42:26AM +0100, Sascha Hauer wrote:
> > On Thu, Jan 11, 2018 at 03:40:49PM +0000, Dgien, David [US] (MS) wrote:
> > > Hello,
> > > 
> > > When going through the archives it looks like a set of patches
> > > were submitted to support device tree overlays in barebox in
> > > http://lists.infradead.org/pipermail/barebox/2015-March/022674.html.
> > > But they weren't accepted because overlays weren't fully
> > > implemented in the DTC yet.
> > > 
> > > It looks like overlay support was mainlined in the kernel in
> > > 4.11. ( kernel/git/torvalds/linux.git:
> > > be5165a51d2500ae1afa1236a8b09858831fdf7e )
> > 
> > I am still not sure which parts got merged and which are still pending.
> > There are still overlay patches floating around.
> 
> The only thing that's missing in the kernel at the moment is a
> user-space interface to load overlays, but the rest has been there for
> quite some time.
> 
> > > Would it be possible to take another look at pulling these patches
> > > into the barebox mainline?
> > 
> > Generally yes. If you like, please rebase test and respin the patches.
> 
> The libfdt gained support to apply overlays quite some time ago
> already, so this should be as easy as updating it to a recent enough
> version, and creating a wrapper around fdt_apply. This is what U-Boot
> is doing.

barebox does not use libfdt.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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