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: Tue, 24 Jul 2012 18:55:37 +0000 Message-ID: <201207241855.37568.arnd@arndb.de> References: <1335820679-28721-1-git-send-email-jon-hunter@ti.com> <201207240719.03601.arnd@arndb.de> <500EC7A5.6020907@wwwdotorg.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.17.8]:57545 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753086Ab2GXTZc (ORCPT ); Tue, 24 Jul 2012 15:25:32 -0400 In-Reply-To: <500EC7A5.6020907@wwwdotorg.org> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Stephen Warren Cc: Vinod Koul , linux-arm-kernel@lists.infradead.org, Stephen Warren , Benoit Cousson , device-tree , Nicolas Ferre , Rob Herring , Grant Likely , Jassi Brar , Jon Hunter , Russell King - ARM Linux , dan.j.williams@intel.com, linux-omap On Tuesday 24 July 2012, Stephen Warren wrote: > It seems that given there are two values for dma-names, there really are > two channels; it's just that one channel is bi-directional, and the > second has two alternatives. > > Still, I guess you could also view this as three separate channels > instead. In which case, the text below makes sense. > > > 3. A device with three channels, one of which has two alternatives: > > > > dmas = <&dma0 1 4 /* first channel, data read */ > > &dma0 2 6 /* second channel, data write */ > > &dma1 1 0 /* third channel, error read */ > > &dma2 1 0>; /* third channel, ernative error read */ > > dma-names = "data", "data", "error", "error"; > > A bidirectional channel would have only one request line, not two, and we would write that as dmas = <&dma0 3 4>; /* one channel on dmarq 4, read-write */ Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 24 Jul 2012 18:55:37 +0000 Subject: [PATCH V3 1/2] of: Add generic device tree DMA helpers In-Reply-To: <500EC7A5.6020907@wwwdotorg.org> References: <1335820679-28721-1-git-send-email-jon-hunter@ti.com> <201207240719.03601.arnd@arndb.de> <500EC7A5.6020907@wwwdotorg.org> Message-ID: <201207241855.37568.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 24 July 2012, Stephen Warren wrote: > It seems that given there are two values for dma-names, there really are > two channels; it's just that one channel is bi-directional, and the > second has two alternatives. > > Still, I guess you could also view this as three separate channels > instead. In which case, the text below makes sense. > > > 3. A device with three channels, one of which has two alternatives: > > > > dmas = <&dma0 1 4 /* first channel, data read */ > > &dma0 2 6 /* second channel, data write */ > > &dma1 1 0 /* third channel, error read */ > > &dma2 1 0>; /* third channel, ernative error read */ > > dma-names = "data", "data", "error", "error"; > > A bidirectional channel would have only one request line, not two, and we would write that as dmas = <&dma0 3 4>; /* one channel on dmarq 4, read-write */ Arnd