Date: Sat, 10 May 2014 23:33:17 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Hans Petter Selasky <hps@selasky.org> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>, Alexander Motin <mav@freebsd.org>, Ian Lepore <ian@freebsd.org> Subject: Re: USB isochronous traffic with Rasberry Pi [WAS: Re: USB audio device on Raspberry Pi] Message-ID: <CAJ-VmokstDSbR1tRRS6vkY4kiqu2fFmfOfRxR1amr2dE3Q3T5g@mail.gmail.com> In-Reply-To: <536F17A1.8060807@selasky.org> References: <20140425154430.GA76168@utility-01.thismonkey.com> <CAGW5k5bZ_bTQUXuzNm=tbwx3npz1_HoOR3vM8TBRVFs8zWCq-w@mail.gmail.com> <5362638B.1080104@selasky.org> <5363C133.2000304@selasky.org> <53677CB8.5000800@selasky.org> <CAJ-Vmo=XmH-RX6_i13NuAXhq-jTC%2BWedGiyOMJaPO4r014DSgw@mail.gmail.com> <1399303695.22079.239.camel@revolution.hippie.lan> <1399304157.22079.243.camel@revolution.hippie.lan> <CAJ-Vmok-%2B7%2Bcq%2BDa6_C2AA7BuP5readY_Gfwwm_RF5kh4VerQA@mail.gmail.com> <5368A93D.3070608@selasky.org> <5368AC03.8080401@selasky.org> <536CE5E9.8020408@selasky.org> <1399647986.22079.367.camel@revolution.hippie.lan> <536D0575.1040407@selasky.org> <1399661378.22079.376.camel@revolution.hippie.lan> <536DDA6D.7060101@selasky.org> <536E2EBB.7030104@selasky.org> <1399742062.22079.403.camel@revolution.hippie.lan> <536EA597.3070700@selasky.org> <536EA753.40905@selasky.org> <1399764190.22079.425.camel@revolution.hippie.lan> <536F17A1.8060807@selasky.org>
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Nah, we fixed it in mips. there's dirty, dirty assembler in the
exception handlr and idle loop calls to skip over the idle loop if an
interrupt comes in.
-a
On 10 May 2014 23:24, Hans Petter Selasky <hps@selasky.org> wrote:
> On 05/11/14 01:23, Ian Lepore wrote:
>>
>> On Sun, 2014-05-11 at 00:25 +0200, Hans Petter Selasky wrote:
>>>
>>> Hi,
>>>
>>> This patch fixes the problem too:
>>>
>>> diff --git a/sys/arm/arm/machdep.c b/sys/arm/arm/machdep.c
>>> index 0490be7..8d53fab 100644
>>> --- a/sys/arm/arm/machdep.c
>>> +++ b/sys/arm/arm/machdep.c
>>> @@ -432,8 +432,12 @@ cpu_idle(int busy)
>>> cpu_idleclock();
>>> }
>>> #endif
>>> + register_t s;
>>> + s = intr_disable();
>>> if (!sched_runnable())
>>> cpu_sleep(0);
>>> + intr_restore(s);
>>> +
>>> #ifndef NO_EVENTTIMERS
>>> if (!busy) {
>>> cpu_activeclock();
>>>
>>> It appears some IRQ is happening when sched_runnable() is running, and
>>> then cpu_sleep(0) is executed even though sched_runnable() is no longer
>>> true.
>>>
>>> --HPS
>>
>>
>> Aha! Now I think you're on to something. Even after explaining why
>> interrupts should be disabled for WFI I didn't notice that we don't
>> disable interrupts before WFI. (I wonder if this is why I sometimes see
>> a lost timer interrupt and have to hit a key to un-wedge things.)
>>
>> Can you try the attached? The spinlock_enter/exit calls are essentially
>> a combination of disabling interrupts and doing a critical_enter().
>>
>> -- Ian
>
>
> Hi Ian,
>
> Your patch works!
>
> BTW: I see the "mips" platform might have a similar issue.
>
>
> --HPS
>
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