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Date:   Thu, 11 May 2023 09:47:12 +0100
Message-ID: <86zg6bmezz.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Rich Felker <dalias@libc.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] irqchip/jcore-aic: Fix missing allocation of IRQ descriptors
In-Reply-To: <3c76bea5e45a5ae9ea58b3ff87f9971955a3a021.camel@physik.fu-berlin.de>
References: <20230510163343.43090-1-glaubitz@physik.fu-berlin.de>
        <479a18513b9d8c6e8ccb96093a0f0dd7@kernel.org>
        <3c76bea5e45a5ae9ea58b3ff87f9971955a3a021.camel@physik.fu-berlin.de>
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On Thu, 11 May 2023 08:22:20 +0100,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> wrote:
> 
> Hi Jason!

???

> 
> On Thu, 2023-05-11 at 07:56 +0100, Marc Zyngier wrote:
> > On 2023-05-10 17:33, John Paul Adrian Glaubitz wrote:
> > > The initialization function for the J-Core AIC aic_irq_of_init() is
> > > currently missing the call to irq_alloc_descs() which allocates and
> > > initializes all the IRQ descriptors. Add missing function call and
> > > return the error code from irq_alloc_descs() in case the allocation
> > > fails.
> > > 
> > > Fixes: 981b58f66cfc ("irqchip/jcore-aic: Add J-Core AIC driver")
> > > Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
> > > ---
> > >  drivers/irqchip/irq-jcore-aic.c | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > > 
> > > diff --git a/drivers/irqchip/irq-jcore-aic.c 
> > > b/drivers/irqchip/irq-jcore-aic.c
> > > index 5f47d8ee4ae3..b9dcc8e78c75 100644
> > > --- a/drivers/irqchip/irq-jcore-aic.c
> > > +++ b/drivers/irqchip/irq-jcore-aic.c
> > > @@ -68,6 +68,7 @@ static int __init aic_irq_of_init(struct device_node 
> > > *node,
> > >  	unsigned min_irq = JCORE_AIC2_MIN_HWIRQ;
> > >  	unsigned dom_sz = JCORE_AIC_MAX_HWIRQ+1;
> > >  	struct irq_domain *domain;
> > > +	int ret;
> > > 
> > >  	pr_info("Initializing J-Core AIC\n");
> > > 
> > > @@ -100,6 +101,12 @@ static int __init aic_irq_of_init(struct 
> > > device_node *node,
> > >  	jcore_aic.irq_unmask = noop;
> > >  	jcore_aic.name = "AIC";
> > > 
> > > +	ret = irq_alloc_descs(-1, min_irq, dom_sz - min_irq,
> > > +			      of_node_to_nid(node));
> > > +
> > > +	if (ret < 0)
> > > +		return ret;
> > > +
> > >  	domain = irq_domain_add_legacy(node, dom_sz - min_irq, min_irq, 
> > > min_irq,
> > >  				       &jcore_aic_irqdomain_ops,
> > >  				       &jcore_aic);
> > 
> > [- Jason]
> > 
> > It really begs the question: how has it ever been working before?
> 
> Users already used a locally patched kernel to work around this problem.

You're not answering my question. Does it mean JCore never worked
upstream?

> > Is there any plan to modernise the port and get it to allocate
> > irq_descs on demand, as we do on most architectures?
> 
> Yes, there are plans to modernize the port. We're first working on
> upstreaming all kinds of patches that have been queuing up over the
> time.

I'd rather you skip that step and focus on making it work as a modern
architecture. This really looks like ARM circa 2007... :-/

	M.

-- 
Without deviation from the norm, progress is not possible.