[PATCH 5/8] imx8m: enable usb power domain

[Marek Vasut]

On 10/12/20 11:20 AM, Peng Fan wrote:
>> Subject: Re: [PATCH 5/8] imx8m: enable usb power domain
>>
>> On 10/12/20 8:23 AM, Peng Fan wrote:
>>> Enable usb power domain, we are not using a power domain driver now.
>>> Currently NXP use a ARM SIP based power domain driver, but this has
>>> been rejected by Linux Kernel, so we are thinking SCMI, however kernel
>>> stuff still not settle down, to make uboot feature work, we directly
>>> use SIP call for U-Boot and MMIO for SPL.
>>
>> The i.MX8M power domain support was already submitted to mainline Linux
>> [1], and it is much nicer to let the OS (or in this case, U-Boot) do that rather
>> than hiding it into ATF.
> 
> oh.. that will conflict with NXP release. I not think NXP will use that in a short time.

How does it conflict with NXP release ?

Note that I agree with Lucas that power management should be done
completely in the OS, the OS knows best what it needs from the hardware.
Splitting it between the OS and firmware will only lead to problems, and
you often cannot fix those easily as you cannot update the firmware, so
that makes it particularly hard for upstream to keep the platform well
supported, the OS would have to support all the various firmware
versions and its bugs and workarounds for those.

> We wanna use SCMI to hide the complex gpc stuff from Linux side and make
> us easy support QNX/Windows/Linux.

I think you want to check the argument between Lucas and Jacky, and you
might want to discuss it there in fact, so we don't have to duplicate
that discussion here .

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