Re: [RFC PATCH 0/6] Boot logo supplied by the device tree

["Uwe Kleine-König" <u.kleine-koenig@baylibre.com>]

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Hello Màxim,

On Sun, Aug 02, 2026 at 12:01:58AM +0200, Màxim Pedraza Padilla wrote:
> Uwe Kleine-König wrote:
> > My 0.02€: Usually you want to use the display using drm and not fb once
> > the machine is fully booted. If you're using fb during boot to display a
> > logo, it's hardly possible to switch to drm later in the boot process
> > without flicker.
> >
> > So my recommendation for your usecase is to not use the kernel boot logo
> > stuff, but something like https://github.com/pengutronix/platsch.
> 
> Thanks for the pointer, I did not know platsch and it looks like a good
> fit for the problem it solves. It does not solve mine, though, and I
> think the reason is worth spelling out, because it is not about how the
> image gets drawn but about when.
> 
> These are industrial units, and the requirement is time to first pixel
> after power is applied. If the panel stays dark for more than a moment
> the unit reads as dead, and that is a support call. Anything running in
> userspace is by construction later than the kernel: it needs the kernel
> booted, the rootfs mounted and init far enough along to exec it. I can
> measure the exact difference on our hardware if that is useful for the
> discussion.

No need to wait for init, the idea is to use init=/usr/sbin/platsch so
it starts before init (and once the display is setup execve()s
/sbin/init). Also you can put it in an initramfs which gets rid of the
dependency on "rootfs mounted". And if your kernel is modular apart from
what is needed for the display the time difference between kernel boot
image and platsch might be negligible compared to the simplification of
the software architecture.

Having said that, I'm against putting boot splash info in the device
tree as the pointed out alternative is IMHO good enough. But my opinion
probably isn't the one that eventually counts.

Best regards
Uwe

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