linux-kernel - Re: [PATCH V2 13/14] dt-bindings: arm-gic: Add documentation for Tegra210 AGIC

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Message-ID: <CAL_Jsq+HSH7e1T9y47nHV_x5NvZ-52cfDEKKFkr16ax671FxSw@mail.gmail.com>
Date:	Wed, 11 May 2016 10:51:57 -0500
From:	Rob Herring <robh+dt@...nel.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Jon Hunter <jonathanh@...dia.com>,
	Mark Rutland <mark.rutland@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Kevin Hilman <khilman@...nel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 13/14] dt-bindings: arm-gic: Add documentation for
 Tegra210 AGIC

On Sat, May 7, 2016 at 9:10 AM, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> Hi Jon,
>
> On Fri, May 6, 2016 at 10:32 AM, Jon Hunter <jonathanh@...dia.com> wrote:
>>> The "nvidia,tegra210-agic" string can be taken as describing any
>>> Tegra-210 specific integration quirks, though I agree that's also not
>>> fantastic for extending PM support beyond Tegra 210 and variants
>>> thereof.
>>>
>>> So maybe the best approach is bailing out in the presence of clocks
>>> and/or power domains after all, on the assumption that nothing today has
>>> those properties, though I fear we may have problems with that later
>>> down the line if/when people describe those for the root GIC to describe
>>> those must be hogged, even if not explicitly managed.
>>
>> On further testing, by bailing out in the presence of clocks and/or
>> power-domains, the problem I now see is that although the primary gic-400
>> has been registered, we still try to probe it again later as it matches
>> the platform driver. One way to avoid this would be ...
>>
>> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
>> index e7bfc175b8e1..631da7ad0dbf 100644
>> --- a/drivers/of/irq.c
>> +++ b/drivers/of/irq.c
>> @@ -556,6 +556,8 @@ void __init of_irq_init(const struct of_device_id *matches)
>>                          * its children can get processed in a subsequent pass.
>>                          */
>>                         list_add_tail(&desc->list, &intc_parent_list);
>> +
>> +                       of_node_set_flag(desc->dev, OF_POPULATED);
>>                 }
>
> That sounds like the right thing to do to me...

Seems fine to me, but it would be a problem since this is a global
decision if you wanted to have some hand-off from an "early driver" to
a platform driver. I guess setting the flag could move to drivers that
need it although I don't think drivers should be touching the flags.

>> If this is not appropriate then I guess I will just need to use
>> "tegra210-agic" for the compatibility flag.
>
> As I want this for plain gic-400, I'd be unhappy ;-)

IMO, the plain gic-400 should not have these dependencies and you
should use SoC specific compatible strings should you need to deal
with this problem.

Rob