From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757533Ab2AKNYS (ORCPT ); Wed, 11 Jan 2012 08:24:18 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:45350 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756547Ab2AKNYQ (ORCPT ); Wed, 11 Jan 2012 08:24:16 -0500 Date: Wed, 11 Jan 2012 21:35:00 +0800 From: Shawn Guo To: Richard Zhao Cc: Eric Miao , patches@linaro.org, vinod.koul@intel.com, linux-kernel@vger.kernel.org, kernel@pengutronix.de, dan.j.williams@intel.com, Richard Zhao , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 6/6] dma/imx-sdma: check whether event_id0 < 32 when set event_mask Message-ID: <20120111133458.GD20968@S2101-09.ap.freescale.net> References: <1326178910-14044-1-git-send-email-richard.zhao@linaro.org> <1326178910-14044-6-git-send-email-richard.zhao@linaro.org> <20120110142008.GE26599@S2101-09.ap.freescale.net> <20120110142939.GB2019@richard-laptop> <20120110153836.GA27831@S2101-09.ap.freescale.net> <20120111005322.GB2414@b20223-02.ap.freescale.net> <20120111014730.GE2414@b20223-02.ap.freescale.net> <20120111131615.GC20968@S2101-09.ap.freescale.net> <20120111130910.GC27484@b20223-02.ap.freescale.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120111130910.GC27484@b20223-02.ap.freescale.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 11, 2012 at 09:09:11PM +0800, Richard Zhao wrote: > On Wed, Jan 11, 2012 at 09:16:17PM +0800, Shawn Guo wrote: > > On Wed, Jan 11, 2012 at 02:37:08PM +0800, Eric Miao wrote: > > > I think Richard has made the issue quite clear here, the original > > > > Yes, he has made it clear, but only after I asked for more comments, > > not with the empty commit message. > > > > > code does seem to have some problems even to me, who do not > > > understand the very details of the SDMA: > > > > > > - sdmac->event_mask0 = 1 << sdmac->event_id0; > > > - sdmac->event_mask1 = 1 << (sdmac->event_id0 - 32); > > > > > > 1. if sdmac->event_id0 >= 32, which will cause event_mask0 to be incorrect > > > 2. if sdmac->event_id < 32, sdmac->event_mask1 will be incorrect > > > > > My testing tells this is not the case. The event_mask0 will be 0 in > > case 1) and event_mask1 will be 0 in case 2), which is quite what we > > expect. And I do not believe you will see any functionality bug with > > the existing code. > Please see my mail mentioned "we shoud not let it depends on gcc's > behavior." In this case, I would rather believe that the author is smart enough to write the code intentionally based on his good understanding on behavior of arm-gcc. -- Regards, Shawn