Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753669AbcJDMM1 convert rfc822-to-8bit (ORCPT ); Tue, 4 Oct 2016 08:12:27 -0400 Received: from down.free-electrons.com ([37.187.137.238]:57438 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750839AbcJDMMZ (ORCPT ); Tue, 4 Oct 2016 08:12:25 -0400 Date: Tue, 4 Oct 2016 14:12:21 +0200 From: Thomas Petazzoni To: Jean-Francois Moine Cc: =?UTF-8?B?TXlsw6huZQ==?= Josserand , vinod.koul@intel.com, maxime.ripard@free-electrons.com, wens@csie.org, mturquette@baylibre.com, sboyd@codeaurora.org, lgirdwood@gmail.com, broonie@kernel.org, perex@perex.cz, tiwai@suse.com, lee.jones@linaro.org, mark.rutland@arm.com, robh+dt@kernel.org, devicetree@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com, alexandre.belloni@free-electrons.com, dmaengine@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 01/14] dma: sun6i-dma: Add burst case of 4 Message-ID: <20161004141221.55327f1b@free-electrons.com> In-Reply-To: <20161004124011.d7f5754a082d5f17d5185fc4@free.fr> References: <3a2404510b5f8b16ae3bb193982d70f158700b2b.1475571575.git.mylene.josserand@free-electrons.com> <20161004124011.d7f5754a082d5f17d5185fc4@free.fr> Organization: Free Electrons X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1689 Lines: 53 Hello, On Tue, 4 Oct 2016 12:40:11 +0200, Jean-Francois Moine wrote: > > Add the case of a burst of 4 which is handled by the SoC. > > > > Signed-off-by: Mylène Josserand > > --- > > drivers/dma/sun6i-dma.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c > > index 8346199..0485204 100644 > > --- a/drivers/dma/sun6i-dma.c > > +++ b/drivers/dma/sun6i-dma.c > > @@ -240,6 +240,8 @@ static inline s8 convert_burst(u32 maxburst) > > switch (maxburst) { > > case 1: > > return 0; > > + case 4: > > + return 1; > > case 8: > > return 2; > > default: > > -- > > 2.9.3 > > This patch has already been rejected by Maxime in the threads > http://www.spinics.net/lists/dmaengine/msg08610.html > and > http://www.spinics.net/lists/dmaengine/msg08719.html > > I hope you will find the way he wants for this maxburst to be added. I was about to reply to Mylene's e-mail, suggesting that she should add a comment in the code (and maybe in the commit log) to explain why this addition is needed, and also that even though the schematics say that value "1" (max burst size of 4 bytes) is reserved, it is in fact incorrect. The Allwinner BSP code is really using this value, and it's the value that makes audio work, so we believe the datasheet is simply incorrect. We already discussed it with Maxime, so I believe he should agree this time. But I would suggest to have such details explained in the commit log and in a comment in the code. Best regards, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com