[PATCH] event: add an event for livetree fixups

[Tom Rini]

On Mon, Apr 15, 2024 at 11:45:29AM +0100, Caleb Connolly wrote:
> 
> 
> On 12/04/2024 20:45, Tom Rini wrote:
> > On Fri, Apr 12, 2024 at 08:04:02PM +0100, Caleb Connolly wrote:
> > 
> >> Introduce a new EVT_OF_LIVE event to allow for the livetree to be
> >> modified before dm_init_and_scan(). Boards can perform fixups here to
> >> handle incompatibilities between U-Boot drivers and upstream DT.
> >>
> >> This will be used by Qualcomm platforms in future patches to enable
> >> setting the dr_mode property if the board doesn't provide one. This has to be
> >> set before dm_init_and_scan() is called as this property effects the binding of
> >> drivers.
> > 
> > This doesn't quite explain why the answer isn't "fix the device tree
> > source" and instead "perform a live fixup". Thanks.
> 
> Hi Tom,
> 
> I think the specifics here that make this difficult is that on some
> Qualcomm boards there is only one USB controller, which can be muxed
> either to a type-c port or to a USB hub via a DIP switch (the state of
> which cannot easily be read out).
> 
> The DT should therefore either not set dr_mode or set it to OTG. This is
> what Linux expects (and it can do proper role detection).
> 
> The dwc3 driver in U-Boot currently doesn't have the ability to
> dynamically mode switch, this is something I'd like to add (as it would
> let us easily flash these boards from U-Boot as well as boot from USB or
> ethernet), but in the mean time the only way to get these boards into
> host mode (which is the preferred default) is to modify the DT in a way
> that breaks Linux.
> 
> Hence the proposal in this patch.
> 
> If this is ok for you then I'll re-send with this additional context in
> the commit description.

So this seems even more special cased than what I was thinking it was.
Would it really be so hard to just add a dummy driver for a few
compatibles in this case? I prefer having two or three real users of a
use case before designing the abstraction for it. Thanks.

-- 
Tom
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