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Subject: Re: [PATCH V6 01/21] irqchip: tegra: Do not disable COP IRQ during
 suspend
To:     Peter De Schrijver <pdeschrijver@nvidia.com>
Cc:     Sowjanya Komatineni <skomatineni@nvidia.com>,
        thierry.reding@gmail.com, jonathanh@nvidia.com, tglx@linutronix.de,
        jason@lakedaemon.net, marc.zyngier@arm.com,
        linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com,
        pgaikwad@nvidia.com, sboyd@kernel.org, linux-clk@vger.kernel.org,
        linux-gpio@vger.kernel.org, jckuo@nvidia.com, josephl@nvidia.com,
        talho@nvidia.com, linux-tegra@vger.kernel.org,
        linux-kernel@vger.kernel.org, mperttunen@nvidia.com,
        spatra@nvidia.com, robh+dt@kernel.org, devicetree@vger.kernel.org
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <de1723df-8580-32fb-eb9d-e4c02f2b4306@gmail.com>
Date:   Thu, 25 Jul 2019 13:59:09 +0300
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25.07.2019 13:38, Peter De Schrijver пишет:
> 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 пишет:
>>>> 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. ;)

> 
> 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.

Again, that's absolutely useless code for the upstream kernel which
could be removed safely to avoid the confusion, IMHO. I can type a patch
if you're agreeing.