RE: [PATCH v3 2/3] ARCv2: MCIP: Use hwirq instead of virq for resolution of IDU IRQ handlers

[Yuriy Kolerov]

Yes, theoretically this may not work with 1/3 and 2/3. I will merge those patches.

> -----Original Message-----
> From: Vineet Gupta [mailto:vgupta@xxxxxxxxxxxx]
> Sent: Tuesday, November 08, 2016 4:59 AM
> To: Yuriy Kolerov <yuriy.kolerov@xxxxxxxxxxxx>; linux-snps-
> arc@xxxxxxxxxxxxxxxxxxx
> Cc: Alexey.Brodkin@xxxxxxxxxxxx; tglx@xxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 2/3] ARCv2: MCIP: Use hwirq instead of virq for
> resolution of IDU IRQ handlers
> 
> On 11/03/2016 05:23 AM, Yuriy Kolerov wrote:
> > Multicore ARC configurations use IDU (Interrupt Distribution Unit) for
> > distributing of common interrupts. In fact IDU is a interrupt
> > controller on top of main per core interrupt controller.
> >
> > All common IRQs are physically and linearly mapped to per core
> > interrupts. E.g. <0, 1, 2, 3> common IDU interrupts may be mapped to
> > per core <24, 25, 26, 27> interrupts. An initialization code of IDU
> > controller (idu_of_init) creates mappings for all parent interrupts
> > <24, 25, ...> and sets a chained IDU handler for them. In the same
> > time idu_of_init must save the first met parent hwirq (idu_first_irq)
> > thus in future it is possible to figure out what common hwirq has come
> > by subtracting of idu_first_irq from the current parent hwirq (see
> > idu_cascade_isr).
> >
> > The problem is that idu_of_init and idu_cascade_isr use parent virtual
> > IRQs as hardware IRQs and perform all the above-described
> > manipulations on virtual IRQs. But it is wrong and hardware IRQs must be
> used instead.
> 
> Is this series bisectable ?
> 
> So if one only applies patch 1/3 (and not 2/3) - as might happen in case of a
> bisect for some arbit problem, will it still work - to me it seems not.
> 
> >
> > Signed-off-by: Yuriy Kolerov <yuriy.kolerov@xxxxxxxxxxxx>
> > ---
> >  arch/arc/kernel/mcip.c | 20 +++++++++-----------
> >  1 file changed, 9 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c index
> > 72f9179..4f4f04b 100644
> > --- a/arch/arc/kernel/mcip.c
> > +++ b/arch/arc/kernel/mcip.c
> > @@ -219,16 +219,14 @@ static struct irq_chip idu_irq_chip = {
> >
> >  };
> >
> > -static int idu_first_irq;
> > +static irq_hw_number_t idu_first_hwirq;
> >
> >  static void idu_cascade_isr(struct irq_desc *desc)  {
> > -	struct irq_domain *domain = irq_desc_get_handler_data(desc);
> > -	unsigned int core_irq = irq_desc_get_irq(desc);
> > -	unsigned int idu_irq;
> > -
> > -	idu_irq = core_irq - idu_first_irq;
> > -	generic_handle_irq(irq_find_mapping(domain, idu_irq));
> > +	struct irq_domain *idu_domain = irq_desc_get_handler_data(desc);
> > +	irq_hw_number_t core_hwirq =
> irqd_to_hwirq(irq_desc_get_irq_data(desc));
> > +	irq_hw_number_t idu_hwirq = core_hwirq - idu_first_hwirq;
> > +	generic_handle_irq(irq_find_mapping(idu_domain, idu_hwirq));
> >  }
> >
> >  static int idu_irq_map(struct irq_domain *d, unsigned int virq,
> > irq_hw_number_t hwirq) @@ -294,7 +292,7 @@ idu_of_init(struct
> device_node *intc, struct device_node *parent)
> >  	struct irq_domain *domain;
> >  	/* Read IDU BCR to confirm nr_irqs */
> >  	int nr_irqs = of_irq_count(intc);
> > -	int i, irq;
> > +	int i, virq;
> >
> >  	if (!idu_detected)
> >  		panic("IDU not detected, but DeviceTree using it"); @@ -
> 312,11
> > +310,11 @@ idu_of_init(struct device_node *intc, struct device_node
> *parent)
> >  		 * however we need it to get the parent virq and set IDU
> handler
> >  		 * as first level isr
> >  		 */
> > -		irq = irq_of_parse_and_map(intc, i);
> > +		virq = irq_of_parse_and_map(intc, i);
> >  		if (!i)
> > -			idu_first_irq = irq;
> > +			idu_first_hwirq =
> irqd_to_hwirq(irq_get_irq_data(virq));
> >
> > -		irq_set_chained_handler_and_data(irq, idu_cascade_isr,
> domain);
> > +		irq_set_chained_handler_and_data(virq, idu_cascade_isr,
> domain);
> >  	}
> >
> >  	__mcip_cmd(CMD_IDU_ENABLE, 0);
> >