linux-kernel - Re: [PATCH v2 5/5] arm64: irqchip/gic-v3: Select priorities at boot time

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Date: Fri, 21 Jun 2024 14:23:54 +0800
From: "Liao, Chang" <liaochang1@...wei.com>
To: Mark Rutland <mark.rutland@....com>,
	<linux-arm-kernel@...ts.infradead.org>
CC: <alexandru.elisei@....com>, <catalin.marinas@....com>,
	<linux-kernel@...r.kernel.org>, <maz@...nel.org>, <tglx@...utronix.de>,
	<will@...nel.org>
Subject: Re: [PATCH v2 5/5] arm64: irqchip/gic-v3: Select priorities at boot
 time



在 2024/6/17 19:18, Mark Rutland 写道:
>  	cpus_have_group0 = gic_has_group0();

> +#define __gicv3_prio_to_ns(p)	(0xff & ((p) << 1))
> +#define __gicv3_ns_to_prio(ns)	(0x80 | ((ns) >> 1))

What about refactoring the gic_has_group0() using the mapping macros
between PMR priority and GIC priority like this:

---------------%<-----------------
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -882,6 +882,7 @@ static bool gic_has_group0(void)
 {
        u32 val;
        u32 old_pmr;
+       u32 prio = BIT(8 - gic_get_pribits());

        old_pmr = gic_read_pmr();

@@ -896,12 +897,12 @@ static bool gic_has_group0(void)
         * becomes 0x80. Reading it back returns 0, indicating that
         * we're don't have access to Group0.
         */
-       gic_write_pmr(BIT(8 - gic_get_pribits()));
+       gic_write_pmr(prio);
        val = gic_read_pmr();

        gic_write_pmr(old_pmr);

-       return val != 0;
+       return val != (__gicv3_prio_to_ns(__gicv3_ns_to_prio(prio)));
 }
--------------->%-----------------


-- 
BR
Liao, Chang