From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtpauth.hypersurf.com (smtpauth.hypersurf.com [209.237.0.8]) by ozlabs.org (Postfix) with ESMTP id 15DC3DDDEE for ; Mon, 17 Nov 2008 21:22:26 +1100 (EST) Received: from [192.168.1.37] (66-81-70-236.bayarea.dialup.o1.com [66.81.70.236]) (authenticated bits=0) by smtpauth.hypersurf.com (8.14.2/8.14.2) with ESMTP id mAHAM8EE042925 for ; Mon, 17 Nov 2008 02:22:21 -0800 (PST) Message-ID: <492145BB.7080904@hypersurf.com> Date: Mon, 17 Nov 2008 02:21:47 -0800 From: Kevin Diggs MIME-Version: 1.0 To: linuxppc-dev@ozlabs.org Subject: Re: pmac_zilog debugging ... References: <4914B549.9010805@hypersurf.com> <1226096603.13603.74.camel@pasglop> <491C11B2.1060909@hypersurf.com> <1226612654.7178.84.camel@pasglop> <491CAA32.20307@hypersurf.com> <1226624429.7178.105.camel@pasglop> <49212D61.3080305@hypersurf.com> <1226912422.7178.228.camel@pasglop> In-Reply-To: <1226912422.7178.228.camel@pasglop> Content-Type: text/plain; charset=ISO-8859-1; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Benjamin Herrenschmidt wrote: > > > That's definitely strange. I would expect the kernel to be able to get > interrupts fast enough to service a 1200 bauds serial port. Maybe > there's something else wrong, or an other driver causing undue interrupt > latencies.... > As far as I can see the system is NOT busy. I see no evidence of excessive interrupt loading. It does have an Adaptec 2940 u2w SCSI card, an ATI video card, and a USB/firewire card. The SCSI card has some disks on it. The other two cards are unused. I guess, in theory, something in my 2.6.27 kernel could be causing one of the two unused cards to throw spurious interrupts? I still think the hardware is mis-behaving. > Out of curiosity, check that IDE properly unmasks interrupts (hdparm > -u1 /dev/hda). > This is an 8600. It is SCSI only (the onboard controller is the MESH). > >> So, I'm on board with this approach. Since I don't really know what I am >>doing, how do you recommend I proceed? > > > Google for a document called MacTech.pdf which contains various > documentations for bits of the ancestor of the IO chip in your machine, > along with a description of the DBDMA engine :-) Something else you can > do is to look at how it's properly used by other drivers such as bmac > and look at some of the darwin source code for reference on how the HW > works. > where might one find older Darwin source? > Cheers, > Ben. > > _______________________________________________ >