From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH V3 1/2] of: Add generic device tree DMA helpers Date: Thu, 21 Jun 2012 14:56:56 +0000 Message-ID: <201206211456.56933.arnd@arndb.de> References: <1335820679-28721-1-git-send-email-jon-hunter@ti.com> <201206151127.24386.arnd@arndb.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.171]:58045 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757690Ab2FUO5h (ORCPT ); Thu, 21 Jun 2012 10:57:37 -0400 In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Guennadi Liakhovetski Cc: Jon Hunter , Stephen Warren , Benoit Cousson , Stephen Warren , device-tree , Nicolas Ferre , Rob Herring , Grant Likely , Jassi Brar , Russell King , linux-omap , linux-arm , Magnus Damm On Thursday 21 June 2012, Guennadi Liakhovetski wrote: > Indeed, this solution should be good enough, thanks! I'm not sure, whether > making this multiplexing available requires any additional code to the > generic DMA DT binding implementation. If it does - please, let's make > this a part of the implementation. It depends how the dma engine gets represented in Linux then: Either we make the common dmaengine code handle multiple dma-engines with the same of_node pointer, or you make the driver register a single dma-engine to Linux that is backed by the three physical devices but just one of_node pointer. I think either way will work, and someone has to try it to determine which one is simpler. > It is also important to provide a flexible multiple channel per device > configuration support to let slave drivers distinguish between different > DMA channels, that they get back from the API. But I think this is a part > of the current proposal and is being taken care of. Yes, it is. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Thu, 21 Jun 2012 14:56:56 +0000 Subject: [PATCH V3 1/2] of: Add generic device tree DMA helpers In-Reply-To: References: <1335820679-28721-1-git-send-email-jon-hunter@ti.com> <201206151127.24386.arnd@arndb.de> Message-ID: <201206211456.56933.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 21 June 2012, Guennadi Liakhovetski wrote: > Indeed, this solution should be good enough, thanks! I'm not sure, whether > making this multiplexing available requires any additional code to the > generic DMA DT binding implementation. If it does - please, let's make > this a part of the implementation. It depends how the dma engine gets represented in Linux then: Either we make the common dmaengine code handle multiple dma-engines with the same of_node pointer, or you make the driver register a single dma-engine to Linux that is backed by the three physical devices but just one of_node pointer. I think either way will work, and someone has to try it to determine which one is simpler. > It is also important to provide a flexible multiple channel per device > configuration support to let slave drivers distinguish between different > DMA channels, that they get back from the API. But I think this is a part > of the current proposal and is being taken care of. Yes, it is. Arnd