From owner-freebsd-arm@FreeBSD.ORG Sat May 10 23:23:15 2014 Return-Path: Delivered-To: freebsd-arm@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 3EA72541; Sat, 10 May 2014 23:23:15 +0000 (UTC) Received: from mho-01-ewr.mailhop.org (mho-03-ewr.mailhop.org [204.13.248.66]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 678681B35; Sat, 10 May 2014 23:23:14 +0000 (UTC) Received: from c-24-8-230-52.hsd1.co.comcast.net ([24.8.230.52] helo=damnhippie.dyndns.org) by mho-01-ewr.mailhop.org with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.72) (envelope-from ) id 1WjGbp-000BuT-1k; Sat, 10 May 2014 23:23:13 +0000 Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id s4ANNA6L032177; Sat, 10 May 2014 17:23:10 -0600 (MDT) (envelope-from ian@FreeBSD.org) X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 24.8.230.52 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX1+OCVlyU8Bx9cvW8ReLC1x8 Subject: Re: USB isochronous traffic with Rasberry Pi [WAS: Re: USB audio device on Raspberry Pi] From: Ian Lepore To: Hans Petter Selasky In-Reply-To: <536EA753.40905@selasky.org> References: <20140425154430.GA76168@utility-01.thismonkey.com> <5360C0A7.9010407@selasky.org> <1398867266.22079.51.camel@revolution.hippie.lan> <5362638B.1080104@selasky.org> <5363C133.2000304@selasky.org> <53677CB8.5000800@selasky.org> <1399303695.22079.239.camel@revolution.hippie.lan> <1399304157.22079.243.camel@revolution.hippie.lan> <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> <1399724697.22079.386.camel@revolution.hippie.l an> <536E2EBB.7030104@selasky.org> <1399742062.22079.403.camel@revolution.hippie.lan> <536EA597.3070700@selasky.org> <536EA753.40905@selasky.org> Content-Type: multipart/mixed; boundary="=-uGWDOLKFIGU7QklY4t93" Date: Sat, 10 May 2014 17:23:10 -0600 Message-ID: <1399764190.22079.425.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port Cc: "freebsd-arm@freebsd.org" , Alexander Motin X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 10 May 2014 23:23:15 -0000 --=-uGWDOLKFIGU7QklY4t93 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 --=-uGWDOLKFIGU7QklY4t93 Content-Disposition: inline; filename="cpu_idle_spinlock.diff" Content-Type: text/x-patch; name="cpu_idle_spinlock.diff"; charset="us-ascii" Content-Transfer-Encoding: 7bit Index: sys/arm/arm/machdep.c =================================================================== --- sys/arm/arm/machdep.c (revision 265783) +++ sys/arm/arm/machdep.c (working copy) @@ -426,9 +426,9 @@ cpu_idle(int busy) CTR2(KTR_SPARE2, "cpu_idle(%d) at %d", busy, curcpu); + spinlock_enter(); #ifndef NO_EVENTTIMERS if (!busy) { - critical_enter(); cpu_idleclock(); } #endif @@ -437,9 +437,9 @@ cpu_idle(int busy) #ifndef NO_EVENTTIMERS if (!busy) { cpu_activeclock(); - critical_exit(); } #endif + spinlock_exit(); CTR2(KTR_SPARE2, "cpu_idle(%d) at %d done", busy, curcpu); } --=-uGWDOLKFIGU7QklY4t93--