Re: [PATCH v3 00/12] cmd: fdt: Add device tree overlays support

[Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>]

Hi Maxime,

On 26 June 2016 at 23:29, Maxime Ripard
<maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> wrote:
> Hi David,
>
> On Mon, Jun 27, 2016 at 01:37:19AM +1000, David Gibson wrote:
>> On Fri, Jun 24, 2016 at 04:27:45PM +0200, Maxime Ripard wrote:
>> > Hi,
>> >
>> > The device tree overlays are a great solution to the issue raised by
>> > the bunch expandable boards we find everywhere these days, like the
>> > Beaglebone, Raspberry Pi or CHIP.
>> >
>> > However, most of the time, the overlays are applied through a
>> > mechanism involving the firmware request interface in Linux, that is
>> > only fully functional once the userspace has been mounted and is
>> > running.
>> >
>> > Some expansion boards might need to be enabled before that, because
>> > they simply need to patch the DT early on, or need to be initialized
>> > early in order to be fully functional, or because they provide access
>> > to the root filesystem.
>> >
>> > In these cases, having the bootloader applying the overlay before
>> > Linux starts seems like the easiest solution.
>> >
>> > This implementation doesn't provide all the Linux fancyness though,
>> > there's no transactional application, which means that if the overlay
>> > cannot be applied for a reason while you're still halfway through the
>> > application, you're probably screwed. It also cannot remove an
>> > overlay, but I don't think that it is currently a use-case.
>> >
>> > There's still a bunch of work to extend the libfdt unit tests to test
>> > the new functions introduced, but these patches will be submitted
>> > in a near future.
>>
>> Are you planning to send a new version of (the relevant portions of)
>> these against upstream libfdt?
>
> Of course, I just only have to work on the test cases now.
>
> Simon wanted to merge this in U-Boot for the next merge window, and
> then sync with libfdt when it would be merged, hence why I posted it
> first.

Yes I'll wait until after the current release as it is too close. Feel
free to send a fix-up patch (or whatever means you prefer) once this
is applied upstream.

Regards,
Simon