Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755349AbaDNL4p (ORCPT ); Mon, 14 Apr 2014 07:56:45 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:33513 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755278AbaDNL4m (ORCPT ); Mon, 14 Apr 2014 07:56:42 -0400 Message-ID: <534BCCD3.9060805@ti.com> Date: Mon, 14 Apr 2014 14:56:03 +0300 From: Peter Ujfalusi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Vinod Koul CC: Sekhar Nori , , , , , , , , , Mark Brown , Lars-Peter Clausen , Liam Girdwood , Takashi Iwai Subject: Re: [PATCH v2 05/14] arm: common: edma: Select event queue 1 as default when booted with DT References: <1396357575-30585-1-git-send-email-peter.ujfalusi@ti.com> <1396357575-30585-6-git-send-email-peter.ujfalusi@ti.com> <5347A4FD.1030803@ti.com> <5347ACDE.7040407@ti.com> <5347AE49.5020109@ti.com> <5347B7F8.2000508@ti.com> <20140411094217.GA32284@intel.com> <5347D2CC.4030407@ti.com> <20140411113154.GB32284@intel.com> <5347DEDA.2060008@ti.com> <20140411124641.GC32284@intel.com> In-Reply-To: <20140411124641.GC32284@intel.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Vinod, On 04/11/2014 03:46 PM, Vinod Koul wrote: > I think the number shouldn't be viewed in absolute terms. If we decide that (lets > say) 0-7, then any controller should map 0 to lowest and 7 to highest. > > For your case you can do this and then intermediate numbers would be medium > priority. Such a system might work well... > > Also how would a client driver know which priority to use? Would it come from > DT? I think DT would be the best place. Not sure if we should set the range for this either. What I was thinking is to add an optional new property to be set by the client nodes, using DMA: mcasp0: mcasp@48038000 { compatible = "ti,am33xx-mcasp-audio"; ... dmas = <&edma 8>, <&edma 9>; dma-names = "tx", "rx"; dma-priorities = <2>, <2>; }; We could agree that lower number means lower priority, higher is - well - higher priority. If the dma-priority is missing we should assume lowest priority (0). The highest priority depends on the platform. For eDMA3 in AM335x it is three level. For designware controller you might have the range 0-8 as valid. The question is how to get this information into use? We can take the priority number in the core when the dma channel is requested and add field to "struct dma_chan" in order to store it and the DMA drivers could have access to it. In this way we only need to update the nodes which needs non default priority for DMA. What do you think? -- P?ter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/