[PATCH v2 04/10] arm64: dts: imx8mn: Add access-controller references

[Peng Fan]

> Subject: Re: [PATCH v2 04/10] arm64: dts: imx8mn: Add access-
> controller references
> 
> Hi Peng,
> 
> Am Freitag, 7. Februar 2025, 13:02:13 CET schrieb Peng Fan:
> > On Fri, Feb 07, 2025 at 09:36:09AM +0100, Alexander Stein wrote:
> > >Mark ocotp as a access-controller and add references on peripherals
> > >which can be disabled (fused).
> >
> > I am not sure whether gpcv2 changes should be included in this
> > patchset or not. Just add access-controller for fused IP will not work.
> 
> Well, I was able to successfully boot a i.MX8M Nano DualLite.
> 
> > i.MX8M BLK-CTRL/GPC will hang if the related power domain is still
> > touched by kernel. The pgc can't power up/down because clock is
> gated.
> 
> Well, with GPU node disabled, no one should enable the power domain.
> But to be on the safe side I would also add access-controllers to the
> corresponding power domains as well.
> 
> > This comment also apply to i.MX8MM/P.
> 
> Sure. Do you have any information what is actually disabled by those
> fused?
> It seems it's the IP and their power domains. Anything else?

In NXP downstream there is a patch for  drivers/pmdomain/imx/imx8m-blk-ctrl.c

soc: imx8m-blk-ctrl: Support fused modules
    
    For fused module, its pgc can't power up/down and clock is gated.
    Because imx8m-blk-ctrl driver will pm_runtime_get_sync/pm_runtime_put
    all power domains during suspend/resume. So we have to remove the
    pgc and clock of fused module from blk-ctrl DTS node.
    Update the driver to support such case.

But this patch also needs U-Boot to update device tree nodes,
I recalled that U-Boot will remove gpc nodes, but not update blk-ctrl nodes.

Regards,
Peng.
> 
> Best regards,
> Alexander
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