From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 9E3D31A03F6 for ; Tue, 3 Nov 2015 09:24:35 +1100 (AEDT) Message-ID: <1446503074.31246.1.camel@ellerman.id.au> Subject: Re: [PATCH] nx-842: Ignore bit 3 of condition register returned by icswx From: Michael Ellerman To: Ram Pai Cc: linuxppc-dev@lists.ozlabs.org, hbabu@us.ibm.com, nacc@us.ibm.com, Dan Streetman Date: Tue, 03 Nov 2015 09:24:34 +1100 In-Reply-To: <20151102184117.GC22547@ram.oc3035372033.ibm.com> References: <20151030223120.GA22550@ram.oc3035372033.ibm.com> <1446427416.31303.1.camel@ellerman.id.au> <20151102184117.GC22547@ram.oc3035372033.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2015-11-02 at 10:41 -0800, Ram Pai wrote: > On Mon, Nov 02, 2015 at 12:23:36PM +1100, Michael Ellerman wrote: > > On Fri, 2015-10-30 at 15:31 -0700, Ram Pai wrote: > > > icswx occasionally under heavy load sets bit 3 of condition register 0. > > > > Why? > > The hardware manual says that bit is undefined, though it is set under some > conditions. Which hardware manual? Last I checked none of this was documented anywhere public. But the out of date RFC I have does define bit zero to mean something. > > > Currently that bit is interpreted by the driver as a failure, when > > > it should have calmly ignored it. > > > > Should the fix be in icswx or the driver? Please justify your choice. > > Yes there are two solutions. One is icswx macro should not expose that > bit to its consumers. Or the driver/consumers can ignore that bit. I > think it makes more sense to contain it in one place, which is icswx > instruction. Drivers or whoever calls icswx should not know > more than what they need to know. This patch uses the first approach. Yep, I'm fine with doing it in icswx if we're 100% sure the bit is always undefined. > > This sounds like it's fixing a bug so shouldn't the patch go to stable? And if > > so which version(s) should it apply to? > > It should go to stable v4.2. I will tag it to stable, in my next version. Thanks. cheers