From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751898Ab2CIJQo (ORCPT ); Fri, 9 Mar 2012 04:16:44 -0500 Received: from mga09.intel.com ([134.134.136.24]:13515 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751141Ab2CIJQm (ORCPT ); Fri, 9 Mar 2012 04:16:42 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="scan'208";a="116156798" Subject: Re: [PATCH/RFC] dmaengine: add a slave parameter to __dma_request_channel() From: Vinod Koul To: Guennadi Liakhovetski Cc: Russell King - ARM Linux , linux-kernel@vger.kernel.org, "'Jassi Brar'" , Linus Walleij , Magnus Damm , Paul Mundt In-Reply-To: References: <1331101687.24656.319.camel@vkoul-udesk3> <20120307093026.GM17370@n2100.arm.linux.org.uk> <20120307103112.GP17370@n2100.arm.linux.org.uk> <20120307124620.GT17370@n2100.arm.linux.org.uk> <20120307142634.GA18787@n2100.arm.linux.org.uk> <20120307162755.GB18787@n2100.arm.linux.org.uk> <1331188201.4657.51.camel@vkoul-udesk3> <1331204128.4657.54.camel@vkoul-udesk3> <1331206459.4657.59.camel@vkoul-udesk3> <1331211513.4657.67.camel@vkoul-udesk3> Content-Type: text/plain; charset="UTF-8" Date: Fri, 09 Mar 2012 14:51:58 +0530 Message-ID: <1331284918.4657.69.camel@vkoul-udesk3> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-03-08 at 14:18 +0100, Guennadi Liakhovetski wrote: > > Assuming I didn't miss... > > > > The case B can be handled without sweat by platforms channel mapping > > information. > > > > Case A where we don't find that devices exist in map, thus being treated > > as generic DMA channels and can be handled easily in sequence. So when > > someone in Q request a channel it would get first channel in Ps > > > > This way we handle both of them in a transparent manner to both clients > > and controllers. > > > > Perhaps we can also add capability to know that if channel is to be > > searched in map or not - would be anyway required for non slave cases. > > Right, but I don't understand then what this gives us. You propose some > channel maps, that will not be used for your "case A." Which means, for > "case A" nothing changes. So, the reason for this whole thread hasn't been > addressed: how to pass channel configuration to the DMA controller driver. For "Case A" there should be no filtering or any issues even now. You have controller requesting a channel and as long as they get a channel for respective pool, it should work. Or is there anything else which is required in this case? -- ~Vinod