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

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Date:   Fri, 2 Aug 2019 20:35:25 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Peter De Schrijver <pdeschrijver@...dia.com>
Cc:     Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, tglx@...utronix.de,
        jason@...edaemon.net, marc.zyngier@....com,
        linus.walleij@...aro.org, stefan@...er.ch, mark.rutland@....com,
        pgaikwad@...dia.com, sboyd@...nel.org, linux-clk@...r.kernel.org,
        linux-gpio@...r.kernel.org, jckuo@...dia.com, josephl@...dia.com,
        talho@...dia.com, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, mperttunen@...dia.com,
        spatra@...dia.com, robh+dt@...nel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH V6 01/21] irqchip: tegra: Do not disable COP IRQ during
 suspend

02.08.2019 16:05, Peter De Schrijver пишет:
> On Thu, Jul 25, 2019 at 01:59:09PM +0300, Dmitry Osipenko wrote:
>> 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. ;)
>>
> 
> 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.

Okay, it shouldn't hurt to clean up the LIC's code a tad by removing the
COP's bits, will make a patch.