Device Tree Blob support in l4linux

Adam Lackorzynski adam at
Thu Aug 21 23:03:07 CEST 2014

On Tue Aug 19, 2014 at 17:43:29 +0200, Martin Schröder wrote:
> Am 19.08.2014 um 14:25 schrieb Martin Schröder:
> >Hi Adam,
> >
> >I tracked the problem down to l4linux/arch/l4/kernel/arch-arm/setup.c:
> >In static customize_machine(void) either machine_desc->init_machine() is
> >called and the static/generic platform devices are added (and the DT
> >disregarded). If init_machine is not set the DT is parsed instead by
> >of_platform_populate. So I changed in l4.c the .init_machine property to
> >NULL and got all the devices generated from the DT.
> While trying to get fec_main.c probed, I recognized that skipping
> .init_machine is not a good idea, since dma_alloc_coherent fails while
> allocating the memory for the network buffer descriptors in fec_main.c. This
> is due to the missing call of l4io_request_iomem in the "dmamem" device
> L4X_DEVICE_CB. So it seems that both init_machine() and
> of_platform_populate() is needed. If I remove the "else" line from the if
> statement in customize_machine the dma_alloc_coherent succeeds again.

Ok, I should probably rip this all out and do DT only.

> >Now at least I got the pinctrl-mxs.c working (utilizes only memory). But
> >gpoi-mxs.c does not get it's irq and fails probing. What is the correct
> >interrupt-parent definition if the interrupt controller is outside of
> >l4linux?
> Maybe the interrupt-parent adjustment could also be done "in memory" after
> loading the dtb?

I have some still hacky code on my disk which I think handles this. I
have to check and clean this up to commit it.

Adam                 adam at

More information about the l4-hackers mailing list