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Re: missing timer in dts: how to deal ?

Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:
> the i.mx6sx SoC I got working recently includes a single-core cortex A9 CPU.
> As I understand it, all A9 CPUs have the TWD timer, and this is what we
> use for delay and hardclock(). But the imx6sx.dtsi file is missing the
> TWD node ("arm,cortex-a9-twd-timer"), while the imx6qdl.dtsi includes it.
> How can we deal with this ?
> - add the twd node to our copy of the device tree (this is what I did
>   in my tree but didn't commit it). But this patches a file in sys/external
> - fake a node in the in-memory fdt early in boot (but is there a way to do
>   this ? I couldn't find anything related to fake nodes in dev/fdt/ or
>   dev/ofw/)
> - add a non-fdt attachement for TWD (and need to find where and when to
>   attach it - maybe as a child of
>   cpus0 at simplebus0

The way to "patch" a device tree is to put files in sys/arch/arm/dts,
they will be used before the ones in sys/external.

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