Re: [PATCH v3 2/4] irqchip/qcom-pdc: Switch to using IRQCHIP_PLATFORM_DRIVER helper macros

From: Marc Zyngier <maz@kernel.org>
To: Saravana Kannan <saravanak@google.com>
Cc: John Stultz <john.stultz@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jason Cooper <jason@lakedaemon.net>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Android Kernel Team <kernel-team@android.com>,
	lkml <linux-kernel@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@lists.infradead.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Hanks Chen <hanks.chen@mediatek.com>,
	CC Hwang <cc.hwang@mediatek.com>,
	Loda Chou <loda.chou@mediatek.com>,
	steev@kali.org, Nial Peters <uceenpe@ucl.ac.uk>
Subject: Re: [PATCH v3 2/4] irqchip/qcom-pdc: Switch to using IRQCHIP_PLATFORM_DRIVER helper macros
Date: Thu, 06 Aug 2020 20:59:28 +0100	[thread overview]
Message-ID: <4d79a3e9c8c24f8adb6f7ade97d5a9c6@kernel.org> (raw)
In-Reply-To: <CAGETcx89BRdSP6FKjDPU0zapt0ET9_PUr6bjZb9EA-jYn0maFw@mail.gmail.com>

On 2020-08-06 19:05, Saravana Kannan wrote:
> On Thu, Aug 6, 2020 at 5:12 AM Marc Zyngier <maz@kernel.org> wrote:
>> 
>> On 2020-08-06 02:24, John Stultz wrote:

[...]

>> >> + if (par_np == np)
>> >> +         par_np = NULL;
>> >> +
>> >> + /*
>> >> + * If there's a parent interrupt controller and  none of the parent
>> >> irq
>> >> + * domains have been registered, that means the parent interrupt
>> >> + * controller has not been initialized yet.  it's not time for this
>> >> + * interrupt controller to initialize. So, defer probe of this
>> >> + * interrupt controller. The actual initialization callback of this
>> >> + * interrupt controller can check for specific domains as necessary.
>> >> + */
>> >> + if (par_np && !irq_find_matching_host(np, DOMAIN_BUS_ANY))
>> >> +         return -EPROBE_DEFER;
>> >
>> > Yep. We're getting caught on the irq_find_matching_host() check. I'm a
>> > little lost as when I look at the qcom,pdc node in the dtsi its not
>> > under a parent controller (instead the soc node).
>> > Not sure if that's an issue in the dtsi or if par_np check needs to
>> > ignore the soc node and pass null?
>> 
>> I think you have nailed it. This checks for a domain attached to
>> the driver we are about to probe, and this domain cannot possibly
>> exist. Instead, it is the *parent* this should check for, as we
>> depend on it for successful probing.
> 
> Duh! Looks like I made a copy-paste/typo error. The comment clearly
> says I'm trying to check the parent and then I end up checking the
> node getting registered. I'm sure this will fix it.
> 
> Actually Nial sent an email a few hours after your and he had found
> the same issue. He even tested the fix with an irqchip driver and it
> fixed the probe issue.

OK, thanks for confirming. It would have been good if these patches
had seen a bit more testing.

> 
> I'm assuming you'll put up the patch yourself. Please let me know if
> you need me to send one.

I have queued this [1] in -next.

It'd be good if someone (John?) could give a Tested-by.

Thanks,

         M.

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/irqchip-next
-- 
Jazz is not dead. It just smells funny...