Re: [PATCH] ARCv2: intc: Disable all core interrupts by default

From: Vineet Gupta
Date: Wed Feb 08 2017 - 11:09:21 EST


On 02/07/2017 03:04 PM, Yuriy Kolerov wrote:
> The kernel emits a lot of warnings about unexpected IRQs when
> an appropriate driver is not presented. It happens because all
> interrupts in the core controller are enabled by default after
> reset. It would be wise to keep all interrupts masked by default.
>
> Thus disable all local and common interrupts. If CPU consists of
> only 1 core without IDU then it is necessary to disable all
> interrupts in the core interrupt controller. If CPU contains IDU
> it means that there are may be more than 1 cores and common
> interrupts (>= FIRST_EXT_IRQ) must be disabled in IDU.

This is not elegant. core intc needs to do same thing to all interrupts coming in
- irrespective of whether they are funneled via IDU or not.


> Signed-off-by: Yuriy Kolerov <yuriy.kolerov@xxxxxxxxxxxx>
> ---
> arch/arc/kernel/intc-arcv2.c | 19 +++++++++++++++++++

[snip...]

> +
> for (i = NR_EXCEPTIONS; i < irq_bcr.irqs + NR_EXCEPTIONS; i++) {
> write_aux_reg(AUX_IRQ_SELECT, i);
> write_aux_reg(AUX_IRQ_PRIORITY, ARCV2_IRQ_DEF_PRIO);
> +
> + /*
> + * If IDU exists then all common interrupts >= FIRST_EXT_IRQ
> + * are masked by IDU thus disable only local interrupts (below
> + * FIRST_EXT_IRQ). Otherwise disable all interrupts.
> + */
> + if (!mp.idu || i < FIRST_EXT_IRQ)
> + write_aux_reg(AUX_IRQ_ENABLE, 0);

So you seem to assume that anything > FIRST_EXT_IRQ is coming in via IDU which may
not be case.
external Interrupts can be wired to core directly - not via IDU
- 16 .. 23 are cpu private reserved irq
- 24 .. C are common irqs (via IDU)
- C + 1 .. N are cpu private external irqs

so better to disable all irq_bcr.irqs independent of how they are hooked up !

-Vineet