From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCHv5 3/8] ARM: OMAP4460: Workaround for ROM bug because of CA9 r2pX gic control register change Date: Fri, 18 May 2012 07:13:08 -0700 Message-ID: <87likpo9vv.fsf@ti.com> References: <1336989796-26594-1-git-send-email-t-kristo@ti.com> <1336989796-26594-4-git-send-email-t-kristo@ti.com> <87zk99ce5q.fsf@ti.com> <4FB3707B.2080200@ti.com> <4FB39C5A.5080404@ti.com> <87mx586pci.fsf@ti.com> <87txzeybhu.fsf@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from na3sys009aog133.obsmtp.com ([74.125.149.82]:32863 "EHLO na3sys009aog133.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946089Ab2ERONJ convert rfc822-to-8bit (ORCPT ); Fri, 18 May 2012 10:13:09 -0400 Received: by pbbrp8 with SMTP id rp8so5582294pbb.33 for ; Fri, 18 May 2012 07:13:08 -0700 (PDT) In-Reply-To: (Santosh Shilimkar's message of "Fri, 18 May 2012 11:35:36 +0530") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Shilimkar, Santosh" Cc: Tero Kristo , linux-omap@vger.kernel.org, paul@pwsan.com, linux-arm-kernel@lists.infradead.org "Shilimkar, Santosh" writes: > On Thu, May 17, 2012 at 10:45 PM, Kevin Hilman wrote= : [...] >> What's not at all clear is what the ROM code does *after* this. =C2=A0= Does it >> clear both bits? =C2=A0or just bit 0? =C2=A0Since it's r1pX based, I= would expect >> that it doesn't touch anything other than bit 0. >> > Actually since the condition of control register =3D=3D 1 is not sati= sfied, > It re-inits entire GIC thinking it's not configured at all. So everyt= hing > will be cleared and including non-secure GIC dist. enable bit. Aha, that's the missing piece of the puzzle: The ROM code is clearing bits that are unused on r1pX (but used on r2pX). That is the root of this bug and needs more description. Thanks for clarifying. [...] >> Santosh, I do understand what is happening here. =C2=A0But I play du= mb so >> that it will be described in great detail in the changelog so that w= hen >> I forget (and you forget) we can go back to this and get a quick >> understanding of both the bug and the workaround. >> >> Since you are very deeply familiar with this bug, it's understandabl= y >> hard to write this changelog since most things probably seem obvious= to >> you. =C2=A0A suggestion would be to have a few colleagues that are n= ot >> familiar with this bug read the changelog and try and describe it ba= ck >> to you. >> > I agree with you. This is side effect of knowing some BUGs too much. > I will work with Tero so that change log captures more details. Thanks. Maybe Jon Hunter can help review the changelog too. IMO, he is the reigning champion of thorough, descriptive and detailed changelogs. :) Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html