linux-kernel - Re: [PATCH V2] irqchip:gic: change access of gicc

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Date:	Thu, 27 Feb 2014 21:29:30 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Feng Kan <fkan@....com>
Cc:	"tglx\@linutronix.de" <tglx@...utronix.de>,
	"patches\@apm.com" <patches@....com>,
	"linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	Vinayak Kale <vkale@....com>
Subject: Re: [PATCH V2] irqchip:gic: change access of gicc_ctrl register to read modify write.

On Thu, Feb 27 2014 at  9:00:07 pm GMT, Feng Kan <fkan@....com> wrote:
> On Thu, Feb 27, 2014 at 10:54 AM, Marc Zyngier <marc.zyngier@....com> wrote:
>> On Thu, Feb 27 2014 at  6:34:55 pm GMT, Feng Kan <fkan@....com> wrote:
>>> This change is made to preserve the GIC v2 releated bits in the
>>> GIC_CPU_CTRL register (also known as the GICC_CTLR register in spec).
>>> The original code only set the enable/disable group bit in this register.
>>> This code will preserve the bypass bits configured by the bootload except
>>> the enable/disable bit. The main reason for this change is to allow the
>>> bypass bits specified in the v2 spec to remain untouched by the current
>>> GIC code. In the X-Gene platform, the bypass functionality is not used
>>> and bypass must be disabled at all time.
>>>
>>> Signed-off-by: Vinayak Kale <vkale@....com>
>>> Acked-by: Anup Patel <apatel@....com>
>>> Signed-off-by: Feng Kan <fkan@....com>
>>> ---
>>> V2 Changes:
>>>       - only mask off v2 bypass bits
>>>
>>>  drivers/irqchip/irq-gic.c |   22 +++++++++++++++++++---
>>>  1 files changed, 19 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>>> index 341c601..757581b 100644
>>> --- a/drivers/irqchip/irq-gic.c
>>> +++ b/drivers/irqchip/irq-gic.c
>>> @@ -418,6 +418,7 @@ static void gic_cpu_init(struct gic_chip_data *gic)
>>>       void __iomem *dist_base = gic_data_dist_base(gic);
>>>       void __iomem *base = gic_data_cpu_base(gic);
>>>       unsigned int cpu_mask, cpu = smp_processor_id();
>>> +     unsigned int ctrl_mask;
>>>       int i;
>>>
>>>       /*
>>> @@ -449,13 +450,24 @@ static void gic_cpu_init(struct gic_chip_data *gic)
>>>               writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4);
>>>
>>>       writel_relaxed(0xf0, base + GIC_CPU_PRIMASK);
>>> -     writel_relaxed(1, base + GIC_CPU_CTRL);
>>> +
>>> +     ctrl_mask = readl(base + GIC_CPU_CTRL);
>>> +     ctrl_mask |= 0x1;
>>> +     writel_relaxed(ctrl_mask, base + GIC_CPU_CTRL);
>>
>> I think I'm quickly loosing the will to live, or at least to review this
>> patch any further.
> Hang in there Marc, though I had nothing to do with the flood in England. Maybe
> I can instill a bit more will for you to live.

I'll probably survive without your help. In the meantime, if you want
that patch to make it in the tree, you'd better fix it.

	M.
-- 
AAAFNRAA
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