Messages in this thread |  | | Date | Tue, 17 Feb 2015 18:15:15 +0800 | From | "Yun Wu (Abel)" <> | Subject | Re: [PATCH v2 5/6] irqchip: gicv3-its: add support for power down |
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On 2015/2/17 17:29, Marc Zyngier wrote:
> On Sun, 15 Feb 2015 09:32:02 +0000 > Yun Wu <wuyun.wu@huawei.com> wrote: > >> It's unsafe to change the configurations of an activated ITS directly >> since this will lead to unpredictable results. This patch guarantees >> a safe quiescent status before initializing an ITS. > > Please change the title of this patch to reflect what it actually > does. Nothing here is about powering down anything.
My miss, I will fix this in next version.
> >> Signed-off-by: Yun Wu <wuyun.wu@huawei.com> >> --- >> drivers/irqchip/irq-gic-v3-its.c | 32 >> ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) >> >> diff --git a/drivers/irqchip/irq-gic-v3-its.c >> b/drivers/irqchip/irq-gic-v3-its.c index 42c03b2..29eb665 100644 >> --- a/drivers/irqchip/irq-gic-v3-its.c >> +++ b/drivers/irqchip/irq-gic-v3-its.c >> @@ -1321,6 +1321,31 @@ static const struct irq_domain_ops >> its_domain_ops = { .deactivate = >> its_irq_domain_deactivate, }; >> >> +static int its_check_quiesced(void __iomem *base) >> +{ >> + u32 count = 1000000; /* 1s */ >> + u32 val; >> + >> + val = readl_relaxed(base + GITS_CTLR); >> + if (val & GITS_CTLR_QUIESCENT) >> + return 0; >> + >> + /* Disable the generation of all interrupts to this ITS */ >> + val &= ~GITS_CTLR_ENABLE; >> + writel_relaxed(val, base + GITS_CTLR); >> + >> + /* Poll GITS_CTLR and wait until ITS becomes quiescent */ >> + while (count--) { >> + val = readl_relaxed(base + GITS_CTLR); >> + if (val & GITS_CTLR_QUIESCENT) >> + return 0; >> + cpu_relax(); >> + udelay(1); >> + } > > You're now introducing a third variant of a 1s timeout loop. Notice a > pattern? >
I am not sure I know exactly what you suggest. Do you mean I should code like below to keep the coding style same as the other 2 loops?
while (1) { val = readl_relaxed(base + GITS_CTLR); if (val & GITS_CTLR_QUIESCENT) return 0;
count--; if (!count) return -EBUSY;
cpu_relax(); udelay(1); }
Thanks, Abel
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