From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936630AbdAFJT3 (ORCPT ); Fri, 6 Jan 2017 04:19:29 -0500 Received: from relay1.mentorg.com ([192.94.38.131]:58844 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763992AbdAFJSe (ORCPT ); Fri, 6 Jan 2017 04:18:34 -0500 Message-ID: <586F5C90.5070108@mentor.com> Date: Fri, 6 Jan 2017 01:00:00 -0800 From: Jiada Wang User-Agent: Mozilla/5.0 (X11; Linux i686; rv:11.0) Gecko/20120411 Thunderbird/11.0.1 MIME-Version: 1.0 To: "Mark Brown vladimir_zapolskiy@mentor.com" CC: , , , , Subject: Re: [PATCH 1/1] spi: imx: support to set watermark level via DTS References: <20170105061015.7816-1-jiada_wang@mentor.com> <20170105175854.gj5xr5drk5tddzyz@sirena.org.uk> In-Reply-To: <20170105175854.gj5xr5drk5tddzyz@sirena.org.uk> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: svr-orw-mbx-01.mgc.mentorg.com (147.34.90.201) To svr-orw-mbx-03.mgc.mentorg.com (147.34.90.203) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Mark and Vladimir On 01/05/2017 09:58 AM, Mark Brown wrote: > On Thu, Jan 05, 2017 at 03:10:15PM +0900, Jiada Wang wrote: > >> Previously watermark level is configured to fifosize/2, >> DMA mode can be used only when transfer length can be divided >> by 'watermark level * bpw', which makes DMA mode not practical. >> This patch adds new DTS property 'dma-wml', user can configure >> DMA watermark level, by specify 'dma-wml' in corresponding ecspi >> node. > Doesn't this just move the problem around a bit - can we not have the > driver figure out a more sensible watermark for each transfer rather > than fixing one in the DT? I would like to submit another version of patch to adjust watermark level based on transfer length. to use largest number (< fifosize / 2 ) which can divide (transfer_length / bytes_per_work). Thanks, Jiada