From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Barada Subject: Re: JTAG debugging of the kernel Date: Mon, 18 Aug 2008 14:47:28 -0400 Message-ID: <1219085248.24975.118.camel@blackhole> References: <1218812628.24975.89.camel@blackhole> <0680EC522D0CC943BC586913CF3768C00208C16544@dbde02.ent.ti.com> <1218823096.24975.108.camel@blackhole> <48A5D19B.1050407@vocollect.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from mail.logicpd.com ([66.162.60.3]:10414 "EHLO smtp.logicpd.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755839AbYHRSra (ORCPT ); Mon, 18 Aug 2008 14:47:30 -0400 In-Reply-To: <48A5D19B.1050407@vocollect.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Josh Karabin Cc: "Syed Mohammed, Khasim" , "linux-omap@vger.kernel.org" On Fri, 2008-08-15 at 14:57 -0400, Josh Karabin wrote: > Peter Barada wrote: > > On Fri, 2008-08-15 at 23:04 +0530, Syed Mohammed, Khasim wrote: > >>> -----Original Message----- > >>> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Peter > >>> Barada > > >>> Any suggestions on what can cause the JTAG to stop working after the > >>> kernel starts? > >>> > >> I think you should disable Power Management. Which kernel are you using now? > > > > 2.6.22.18. I'm planning to move to 2.6.26 after the dust settles... > > > > I'll try w/o power management, but any idea why power management might > > affect JTAG? > > The guy I share an office with (who's out on vacation) worked through > this with their tech support, who suggested replacing WFI instructions > with NOPs. > > Look at cpu_v7_do_idle in arch/arm/mm/proc-v7.S. Changing the WFI to a > NOP did the trick for him. > > Presumably power management was off, but even WFI (wait for interrupt) > put the CPU in a state that wasn't handled by the BDI firmware at the > time. I'm not sure if they resolved the issue in a later firmware > update or not. We didn't think the workaround was worthy of a Kconfig > option - hopefully updated firmware for the BDI box will address the issue. Hmm, trying both disabling power management and changing the WFI to NOP in cpu_v7_do_idle does not work, the BDI times out when I try to halt the processor. I'm running with version 1.07 of the BDI firmware. Is this what other people are successfully using to debug the kernel with a BDI-2000? > > - Josh