linux-kernel - Re: [PATCH v2 3/4] irqchip: sifive-plic: Differentiate between PLIC handler and context

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Date:   Thu, 29 Nov 2018 17:57:36 -0800
From:   Atish Patra <atish.patra@....com>
To:     Anup Patel <anup@...infault.org>,
        Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/4] irqchip: sifive-plic: Differentiate between PLIC
 handler and context

On 11/27/18 2:04 AM, Anup Patel wrote:
> We explicitly differentiate between PLIC handler and context because
> PLIC context is for given mode of HART whereas PLIC handler is per-CPU
> software construct meant for handling interrupts from a particular
> PLIC context.
> 
> Signed-off-by: Anup Patel <anup@...infault.org>
> ---
>   drivers/irqchip/irq-sifive-plic.c | 21 +++++++++++++--------
>   1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 95b4b92ca9b8..ffd4deaca057 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -66,8 +66,8 @@ static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
>   
>   struct plic_hw {
>   	u32			nr_irqs;
> +	u32			nr_contexts;
>   	u32			nr_handlers;
> -	u32			nr_mapped;
>   	void __iomem		*regs;
>   	struct irq_domain	*irqdomain;
>   };
> @@ -191,10 +191,10 @@ static int __init plic_init(struct device_node *node,
>   	if (WARN_ON(!plic.nr_irqs))
>   		goto out_iounmap;
>   
> -	plic.nr_handlers = of_irq_count(node);
> -	if (WARN_ON(!plic.nr_handlers))
> +	plic.nr_contexts = of_irq_count(node);
> +	if (WARN_ON(!plic.nr_contexts))
>   		goto out_iounmap;
> -	if (WARN_ON(plic.nr_handlers < num_possible_cpus()))
> +	if (WARN_ON(plic.nr_contexts < num_possible_cpus()))
>   		goto out_iounmap;
>   
>   	plic.irqdomain = irq_domain_add_linear(node, plic.nr_irqs + 1,
> @@ -202,7 +202,7 @@ static int __init plic_init(struct device_node *node,
>   	if (WARN_ON(!plic.irqdomain))
>   		goto out_iounmap;
>   
> -	for (i = 0; i < plic.nr_handlers; i++) {
> +	for (i = 0; i < plic.nr_contexts; i++) {
>   		struct of_phandle_args parent;
>   		struct plic_handler *handler;
>   		irq_hw_number_t hwirq;
> @@ -225,6 +225,11 @@ static int __init plic_init(struct device_node *node,
>   
>   		cpu = riscv_hartid_to_cpuid(hartid);
>   		handler = per_cpu_ptr(&plic_handlers, cpu);
> +		if (handler->present) {
> +			pr_warn("handler not available for context %d.\n", i);
> +			continue;
> +		}
> +

Ahh you have the handler->present check here in this patch. This should 
be in the 2nd patch. This change doesn't match the commit text anyways.

Everything else just variable renaming which can be separated.
nr_handlers->nr_contexts
nr_mapped->nr_handlers


Regards,
Atish
>   		handler->present = true;
>   		handler->hart_base =
>   			plic.regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
> @@ -237,11 +242,11 @@ static int __init plic_init(struct device_node *node,
>   		for (hwirq = 1; hwirq <= plic.nr_irqs; hwirq++)
>   			plic_toggle(handler, hwirq, 0);
>   
> -		plic.nr_mapped++;
> +		plic.nr_handlers++;
>   	}
>   
> -	pr_info("mapped %d interrupts to %d (out of %d) handlers.\n",
> -		plic.nr_irqs, plic.nr_mapped, plic.nr_handlers);
> +	pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
> +		plic.nr_irqs, plic.nr_handlers, plic.nr_contexts);
>   	set_handle_irq(plic_handle_irq);
>   	return 0;
>   
>