Re: [PATCH v1 0/5] Enable fw_devlink=on by default

From: Nicolas Saenz Julienne
Date: Wed Jan 13 2021 - 06:45:19 EST


On Thu, 2020-12-17 at 19:16 -0800, Saravana Kannan wrote:
> As discussed in LPC 2020, cyclic dependencies in firmware that couldn't
> be broken using logic was one of the last remaining reasons
> fw_devlink=on couldn't be set by default.
>
> This series changes fw_devlink so that when a cyclic dependency is found
> in firmware, the links between those devices fallback to permissive mode
> behavior. This way, the rest of the system still benefits from
> fw_devlink, but the ambiguous cases fallback to permissive mode.
>
> Setting fw_devlink=on by default brings a bunch of benefits (currently,
> only for systems with device tree firmware):
> * Significantly cuts down deferred probes.
> * Device probe is effectively attempted in graph order.
> * Makes it much easier to load drivers as modules without having to
>   worry about functional dependencies between modules (depmod is still
>   needed for symbol dependencies).

FWIW I don't see any issues with this on Raspberry Pi 4 :).

Regards,
Nicolas

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