Re: [PATCH 07/11] of/irq: Export of_irq_count to drivers

From: Rob Herring <robh+dt@kernel.org>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Russell King <linux@armlinux.org.uk>, Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	"maintainer:BROADCOM BCM281XX/BCM11XXX/BCM216XX ARM ARCHITE..." 
	<bcm-kernel-feedback-list@broadcom.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Marc Zyngier <maz@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Ard Biesheuvel <ardb@kernel.org>, Mike Rapoport <rppt@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Arnd Bergmann <arnd@arndb.de>, Guenter Roeck <linux@roeck-us.net>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
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	Andrey Konovalov <andreyknvl@gmail.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
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Subject: Re: [PATCH 07/11] of/irq: Export of_irq_count to drivers
Date: Mon, 27 Sep 2021 15:09:10 -0500	[thread overview]
Message-ID: <CAL_JsqKyFeSn=6PiFHNZR7oTy9A5VdmD7U3=Za0qyofPB6aoMA@mail.gmail.com> (raw)
In-Reply-To: <ec13207a-08b4-cbc4-7f29-1ce25ce1ebd0@gmail.com>

On Mon, Sep 27, 2021 at 2:49 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>
> On 9/27/21 12:43 PM, Rob Herring wrote:
> > On Mon, Sep 27, 2021 at 2:28 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
> >>
> >> On 9/27/21 12:08 PM, Rob Herring wrote:
> >>> On Fri, Sep 24, 2021 at 12:07 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
> >>>>
> >>>> In order to build drivers/irqchip/irq-bcm7120-l2.c as a module, we will
> >>>> need to have of_irq_count() exported to modules.
> >>>>
> >>>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> >>>> ---
> >>>>  drivers/of/irq.c | 1 +
> >>>>  1 file changed, 1 insertion(+)
> >>>>
> >>>> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> >>>> index 352e14b007e7..949b9d1f8729 100644
> >>>> --- a/drivers/of/irq.c
> >>>> +++ b/drivers/of/irq.c
> >>>> @@ -440,6 +440,7 @@ int of_irq_count(struct device_node *dev)
> >>>>
> >>>>         return nr;
> >>>>  }
> >>>> +EXPORT_SYMBOL_GPL(of_irq_count);
> >>>
> >>> Please convert to use platform_irq_count() instead.
> >>
> >> That requires a platform_device to be passed to platform_irq_count(),
> >> will that work even when the drivers remain built into the kernel and
> >> get initialized early on?
> >
> > No, does your irqchip using this do both? Looks to me like it is
> > always a platform_device.
>
> On ARM/ARM64 not using GKI as well as MIPS, we would want the module to
> be built into the kernel image, however when using GKI that driver would
> become a module. How do you suggest reconciling both usages?

What's there to resolve? Every driver that works as a module can be
built-in. Is there something special about irqchip drivers?

The only issue I see here is platform_irqchip_probe() doesn't pass the
platform_device pointer to the irq_init_cb function. There's 3 ways to
fix that. Add a platform_device pointer to the init hook. That's a
global change though. That's the right thing to do IMO. Or you can use
of_find_device_by_node(). That's fairly expensive, but easy and
isolated. You could also set device_node.data pointer to the
platform_device, but ideally I'd like to get rid of that pointer as
it's hardly used.

Rob