irqchip/sifive-plic: set max threshold for ignored handlers

		struct plic_handler *handler;

		irq_hw_number_t hwirq;

		int cpu, hartid;

		u32 threshold = 0;

		if (of_irq_parse_one(node, i, &parent)) {

			pr_err("failed to parse parent for context %d.\n", i);

			continue;

		}

		/*

		 * When running in M-mode we need to ignore the S-mode handler.

		 * Here we assume it always comes later, but that might be a

		 * little fragile.

		 */

		handler = per_cpu_ptr(&plic_handlers, cpu);

		if (handler->present) {

			pr_warn("handler already present for context %d.\n", i);

			continue;

			threshold = 0xffffffff;

			goto done;

		}

		handler->present = true;

		handler->enable_base =

			plic_regs + ENABLE_BASE + i * ENABLE_PER_HART;

done:

		/* priority must be > threshold to trigger an interrupt */

		writel(0, handler->hart_base + CONTEXT_THRESHOLD);

		writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);

		for (hwirq = 1; hwirq <= nr_irqs; hwirq++)

			plic_toggle(handler, hwirq, 0);

		nr_handlers++;