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Message-ID: <f3fe3e75-b66a-c628-89d2-df405d8241f1@synopsys.com>
Date: Tue, 3 Jan 2017 10:10:45 -0800
From: Vineet Gupta <Vineet.Gupta1@...opsys.com>
To: Yuriy Kolerov <yuriy.kolerov@...opsys.com>,
"linux-snps-arc@...ts.infradead.org"
<linux-snps-arc@...ts.infradead.org>
CC: "Alexey.Brodkin@...opsys.com" <Alexey.Brodkin@...opsys.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"marc.zyngier@....com" <marc.zyngier@....com>
Subject: Re: [PATCH v3 3/3] ARCv2: MCIP: Deprecate setting of affinity in
Device Tree
On 12/28/2016 12:47 AM, Yuriy Kolerov wrote:
> Ignore value of interrupt distribution mode for common interrupts in
> IDU since setting of affinity using value from Device Tree is deprecated
> in ARC. Originally it is done in idu_irq_xlate() function and it is
> semantically wrong and does not guaranty that an affinity value will be
> set properly. idu_irq_enable() function is better place for
> initialization of common interrupts.
>
> By default send all common interrupts to all available online CPUs.
Is this a departure from our original idea to route everything only to boot cpu ?
Otherwise this looks OK to me !
-Vineet
> The affinity of common interrupts in IDU must be set manually since
> in some cases the kernel will not call irq_set_affinity() by itself:
>
> 1. When the kernel is not configured with support of SMP.
> 2. When the kernel is configured with support of SMP but upper
> interrupt controllers does not support setting of the affinity
> and cannot propagate it to IDU.
>
> Signed-off-by: Yuriy Kolerov <yuriy.kolerov@...opsys.com>
> ---
> .../interrupt-controller/snps,archs-idu-intc.txt | 3 ++
> arch/arc/kernel/mcip.c | 52 +++++++++-------------
> 2 files changed, 25 insertions(+), 30 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/snps,archs-idu-intc.txt b/Documentation/devicetree/bindings/interrupt-controller/snps,archs-idu-intc.txt
> index 0dcb7c7..9446576 100644
> --- a/Documentation/devicetree/bindings/interrupt-controller/snps,archs-idu-intc.txt
> +++ b/Documentation/devicetree/bindings/interrupt-controller/snps,archs-idu-intc.txt
> @@ -15,6 +15,9 @@ Properties:
> Second cell specifies the irq distribution mode to cores
> 0=Round Robin; 1=cpu0, 2=cpu1, 4=cpu2, 8=cpu3
>
> + The second cell in interrupts property is deprecated and may be ignored by
> + the kernel.
> +
> intc accessed via the special ARC AUX register interface, hence "reg" property
> is not specified.
>
> diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c
> index be131b2..d492a3c 100644
> --- a/arch/arc/kernel/mcip.c
> +++ b/arch/arc/kernel/mcip.c
> @@ -175,7 +175,6 @@ static void idu_irq_unmask(struct irq_data *data)
> raw_spin_unlock_irqrestore(&mcip_lock, flags);
> }
>
> -#ifdef CONFIG_SMP
> static int
> idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
> bool force)
> @@ -205,12 +204,27 @@ idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
>
> return IRQ_SET_MASK_OK;
> }
> -#endif
> +
> +static void idu_irq_enable(struct irq_data *data)
> +{
> + /*
> + * By default send all common interrupts to all available online CPUs.
> + * The affinity of common interrupts in IDU must be set manually since
> + * in some cases the kernel will not call irq_set_affinity() by itself:
> + * 1. When the kernel is not configured with support of SMP.
> + * 2. When the kernel is configured with support of SMP but upper
> + * interrupt controllers does not support setting of the affinity
> + * and cannot propagate it to IDU.
> + */
> + idu_irq_set_affinity(data, cpu_online_mask, false);
> + idu_irq_unmask(data);
> +}
>
> static struct irq_chip idu_irq_chip = {
> .name = "MCIP IDU Intc",
> .irq_mask = idu_irq_mask,
> .irq_unmask = idu_irq_unmask,
> + .irq_enable = idu_irq_enable,
> #ifdef CONFIG_SMP
> .irq_set_affinity = idu_irq_set_affinity,
> #endif
> @@ -243,36 +257,14 @@ static int idu_irq_xlate(struct irq_domain *d, struct device_node *n,
> const u32 *intspec, unsigned int intsize,
> irq_hw_number_t *out_hwirq, unsigned int *out_type)
> {
> - irq_hw_number_t hwirq = *out_hwirq = intspec[0];
> - int distri = intspec[1];
> - unsigned long flags;
> -
> + /*
> + * Ignore value of interrupt distribution mode for common interrupts in
> + * IDU which resides in intspec[1] since setting an affinity using value
> + * from Device Tree is deprecated in ARC.
> + */
> + *out_hwirq = intspec[0];
> *out_type = IRQ_TYPE_NONE;
>
> - /* XXX: validate distribution scheme again online cpu mask */
> - if (distri == 0) {
> - /* 0 - Round Robin to all cpus, otherwise 1 bit per core */
> - raw_spin_lock_irqsave(&mcip_lock, flags);
> - idu_set_dest(hwirq, BIT(num_online_cpus()) - 1);
> - idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
> - raw_spin_unlock_irqrestore(&mcip_lock, flags);
> - } else {
> - /*
> - * DEST based distribution for Level Triggered intr can only
> - * have 1 CPU, so generalize it to always contain 1 cpu
> - */
> - int cpu = ffs(distri);
> -
> - if (cpu != fls(distri))
> - pr_warn("IDU irq %lx distri mode set to cpu %x\n",
> - hwirq, cpu);
> -
> - raw_spin_lock_irqsave(&mcip_lock, flags);
> - idu_set_dest(hwirq, cpu);
> - idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_DEST);
> - raw_spin_unlock_irqrestore(&mcip_lock, flags);
> - }
> -
> return 0;
> }
>
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