Re: [PATCH V6 01/21] irqchip: tegra: Do not disable COP IRQ during suspend

[Peter De Schrijver]

On Thu, Jul 25, 2019 at 01:59:09PM +0300, Dmitry Osipenko wrote:
> 25.07.2019 13:38, Peter De Schrijver ÐÐÑÐÑ:
> > On Thu, Jul 25, 2019 at 01:33:48PM +0300, Peter De Schrijver wrote:
> >> On Thu, Jul 25, 2019 at 01:05:13PM +0300, Dmitry Osipenko wrote:
> >>> 25.07.2019 12:55, Peter De Schrijver ÐÐÑÐÑ:
> >>>> On Mon, Jul 22, 2019 at 12:54:51PM +0300, Dmitry Osipenko wrote:
> >>>>>
> >>>>> All Tegra SoCs support SC7, hence the 'supports_sc7' and the comment
> >>>>> doesn't sound correct to me. Something like 'firmware_sc7' should suit
> >>>>> better here.
> >>>>>
> >>>>>> +			writel_relaxed(~0ul, ictlr + ICTLR_COP_IER_CLR);
> >>>>>
> >>>>> Secondly, I'm also not sure why COP interrupts need to be disabled for
> >>>>> pre-T210 at all, since COP is unused. This looks to me like it was
> >>>>> cut-n-pasted from downstream kernel without a good reason and could be
> >>>>> simply removed.
> >>>>
> >>>> I don't think we can rely on the fact that COP is unused. People can
> >>>> write their own code to run on COP.
> >>>
> >>> 1. Not upstream - doesn't matter.
> >>>
> >>
> >> The code is not part of the kernel, so obviously it's not upstream?
> >>
> >>> 2. That's not very good if something unknown is running on COP and then
> >>> kernel suddenly intervenes, don't you think so?
> >>
> >> Unless the code was written with this in mind.
> >>
> 
> In that case, please see 1. ;)
> 

In general the kernel should not touch the COP interrupts I think.

> > 
> > Looking at this again, I don't think we need to enable the IRQ at all.
> 
> Could you please clarify? The code only saves/restores COP's interrupts
> context across suspend-resume.

The sc7 entry firmware doesn't use interrupts.

Peter.