From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Karabin Subject: Re: JTAG debugging of the kernel Date: Fri, 15 Aug 2008 14:57:31 -0400 Message-ID: <48A5D19B.1050407@vocollect.com> References: <1218812628.24975.89.camel@blackhole> <0680EC522D0CC943BC586913CF3768C00208C16544@dbde02.ent.ti.com> <1218823096.24975.108.camel@blackhole> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx4.vocollect.com ([64.212.175.114]:2261 "EHLO mx4.vocollect.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754350AbYHOS5f (ORCPT ); Fri, 15 Aug 2008 14:57:35 -0400 In-Reply-To: <1218823096.24975.108.camel@blackhole> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Peter Barada Cc: "Syed Mohammed, Khasim" , "linux-omap@vger.kernel.org" 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. - Josh