linux-kernel - Re: [PATCH V2 18/24] irqchip: mips-gic: Stop using per-platform mapping tables

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Date:	Thu, 15 Jan 2015 16:50:00 +0000
From:	James Hogan <james.hogan@...tec.com>
To:	Qais Yousef <qais.yousef@...tec.com>
CC:	Andrew Bresticker <abrestic@...omium.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Jeffrey Deans <jeffrey.deans@...tec.com>,
	"Markos Chandras" <markos.chandras@...tec.com>,
	Paul Burton <paul.burton@...tec.com>,
	Jonas Gorski <jogo@...nwrt.org>,
	John Crispin <blogic@...nwrt.org>,
	"David Daney" <ddaney.cavm@...il.com>, <linux-mips@...ux-mips.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 18/24] irqchip: mips-gic: Stop using per-platform mapping
 tables

On 15/01/15 16:36, Qais Yousef wrote:
> On 01/15/2015 04:29 PM, James Hogan wrote:
>> On 15/01/15 11:59, James Hogan wrote:
>>> Hi Andrew,
>>>
>>> On 18/09/14 22:47, Andrew Bresticker wrote:
>>>> Now that the GIC properly uses IRQ domains, kill off the per-platform
>>>> routing tables that were used to make the GIC appear transparent.
>>>>
>>>> This includes:
>>>>   - removing the mapping tables and the support for applying them,
>>>>   - moving GIC IPI support to the GIC driver,
>>>>   - properly routing the i8259 through the GIC on Malta, and
>>>>   - updating IRQ assignments on SEAD-3 when the GIC is present.
>>>>
>>>> Platforms no longer will pass an interrupt mapping table to gic_init.
>>>> Instead, they will pass the CPU interrupt vector (2 - 7) that they
>>>> expect the GIC to route interrupts to.  Note that in EIC mode this
>>>> value is ignored and all GIC interrupts are routed to EIC vector 1.
>>>>
>>>> Signed-off-by: Andrew Bresticker <abrestic@...omium.org>
>>>> Acked-by: Jason Cooper <jason@...edaemon.net>
>>>> Reviewed-by: Qais Yousef <qais.yousef@...tec.com>
>>>> Tested-by: Qais Yousef <qais.yousef@...tec.com>
>>> This commit (18743d2781d01d34d132f952a2e16353ccb4c3de) appears to break
>>> boot of interAptiv, dual core, dual vpe per core, on malta with
>>> malta_defconfig.
>>>
>>> It gets to here:
>>> ...
>>> CPU1 revision is: 0001a120 (MIPS interAptiv (multi))
>>> FPU revision is: 0173a000
>>> Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
>>> Primary data cache 64kB, 4-way, PIPT, no aliases, linesize 32 bytes
>>> MIPS secondary cache 1024kB, 8-way, linesize 32 bytes.
>>> Synchronize counters for CPU 1: done.
>>> Brought up 2 CPUs
>>>
>>> and then appears to just hang. Passing nosmp works around it, allowing
>>> it to get to userland.
>>>
>>> Is that a problem you've already come across?
>>>
>>> I'll keep debugging.
>> Right, it appears the CPU IRQ line that the GIC is using doesn't get
>> unmasked (STATUSF_IP2) when a new VPE is brought up, so only the first
>> CPU will actually get any interrupts after your patch (including the
>> rather critical IPIs), i.e. hacking it in vsmp_init_secondary() in
>> smp-mt.c allows it to boot.
>>
>> Hmm, I'll have a think about what the most generic fix is, since
>> arbitrary stuff may or may not have registered handlers for the raw CPU
>> interrupts (timer, performance counter, gic etc)...
>>
>> Cheers
>> James
>>
> 
> Is this similar to the issue addressed by this (ff1e29ade4c6 MIPS:
> smp-cps: Enable all hardware interrupts on secondary CPUs)?

Thanks Qais. Yes, enabling CPS also works around the problem thanks to
that commit.

Cheers
James


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