From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752704AbbANR6m (ORCPT ); Wed, 14 Jan 2015 12:58:42 -0500 Received: from mail-by2on0108.outbound.protection.outlook.com ([207.46.100.108]:56836 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750856AbbANR6k (ORCPT ); Wed, 14 Jan 2015 12:58:40 -0500 Message-ID: <1421258312.4961.133.camel@freescale.com> Subject: Re: [PATCH] powerpc/mpic: Add DT option to skip readback after EOI From: Scott Wood To: Bogdan Purcareata CC: , , Date: Wed, 14 Jan 2015 11:58:32 -0600 In-Reply-To: <1421236622-29366-1-git-send-email-bogdan.purcareata@freescale.com> References: <1421236622-29366-1-git-send-email-bogdan.purcareata@freescale.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [2601:2:5800:3f7:12bf:48ff:fe84:c9a0] X-ClientProxiedBy: BL2PR05CA0036.namprd05.prod.outlook.com (10.255.226.36) To BY2PR0301MB0726.namprd03.prod.outlook.com (25.160.63.16) Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=scottwood@freescale.com; X-DmarcAction-Test: None X-Microsoft-Antispam: UriScan:; X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:(3005003);SRVR:BY2PR0301MB0726; X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004);SRVR:BY2PR0301MB0726; X-Forefront-PRVS: 04569283F9 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(6009001)(189002)(199003)(51704005)(24454002)(377424004)(76176999)(50986999)(64706001)(47776003)(106356001)(110136001)(101416001)(19580395003)(19580405001)(77156002)(62966003)(92566002)(87976001)(103116003)(68736005)(36756003)(2950100001)(46102003)(86362001)(105586002)(97736003)(50226001)(33646002)(50466002)(23676002)(42186005)(122386002)(40100003)(3826002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR0301MB0726;H:[IPv6:2601:2:5800:3f7:12bf:48ff:fe84:c9a0];FPR:;SPF:None;MLV:sfv;PTR:InfoNoRecords;MX:1;A:1;LANG:en; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:;SRVR:BY2PR0301MB0726; X-OriginatorOrg: freescale.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Jan 2015 17:58:37.5580 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY2PR0301MB0726 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2015-01-14 at 11:57 +0000, Bogdan Purcareata wrote: > The readback is necessary in order to handle PCI posted > writes, That is unclear. > or when the MPIC is handling interrupts in a loop > (ppc_md.get_irq). I'm questioning this one as well -- if reading WHOAMI is sufficient to sync with the EOI, why wouldn't reading INTACK work as well? > Newer MPIC versions don't require this readback. Leave the option > configurable using a device tree entry. > > This saves a MMIO trap per interrupt. > > Signed-off-by: Scott Wood > Signed-off-by: Bogdan Purcareata You should note changes (e.g. with a [] note between signoffs) if it differs from the original... -Scott