linux-kernel - Re: [PATCH] spi: bcm2835: do not unregister controller in shutdown handler

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Message-ID: <8513334a-1de4-bc9c-0157-e792e8ff4871@gmail.com>
Date:   Mon, 4 Oct 2021 10:44:34 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Mark Brown <broonie@...nel.org>, Jason Gunthorpe <jgg@...pe.ca>
Cc:     Lino Sanfilippo <LinoSanfilippo@....de>, rjui@...adcom.com,
        sbranden@...adcom.com, bcm-kernel-feedback-list@...adcom.com,
        nsaenz@...nel.org, linux-spi@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        p.rosenberger@...bus.com, linux-integrity@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] spi: bcm2835: do not unregister controller in shutdown
 handler

On 10/4/21 10:27 AM, Mark Brown wrote:
> On Mon, Oct 04, 2021 at 02:13:01PM -0300, Jason Gunthorpe wrote:
> 
>> I'm kind of surprised a scheme like this didn't involve a FW call
>> after Linux is done with the CPUs to quiet all the HW and let it
>> sleep, I've built things that way before at least.
> 
> That's a *lot* of code to put in firmware if you can't physically power
> most of the system down.

Indeed, and that also assume it may be possible for firmware to have the
last say, which is not necessarily possible (though that ought to be a
system design issue that would need fixing). It seems reasonable to me
to delegate the powering off of the hardware to the respective Linux
drivers since they ought to be in the best position to make appropriate
decisions for the hardware they control.

Anyway, we are divergin slightly here, how do we go about fixing
.shutdown here?
-- 
Florian