Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757468Ab3FSULC (ORCPT ); Wed, 19 Jun 2013 16:11:02 -0400 Received: from mga14.intel.com ([143.182.124.37]:63699 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756805Ab3FSULA (ORCPT ); Wed, 19 Jun 2013 16:11:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,899,1363158000"; d="scan'208";a="319618512" Date: Wed, 19 Jun 2013 13:10:54 -0700 From: Jon Mason To: Dan Williams Cc: Vinod Koul , Dave Jiang , Linux Kernel Mailing List Subject: Re: [PATCH 2/2] ioatdma: add DMA_PRIVATE capabilities flag Message-ID: <20130619201054.GA20996@jonmason-lab> References: <1371602813-19828-1-git-send-email-jon.mason@intel.com> <1371602813-19828-3-git-send-email-jon.mason@intel.com> <20130619175206.GA20737@jonmason-lab> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1349 Lines: 32 On Wed, Jun 19, 2013 at 11:56:38AM -0700, Dan Williams wrote: > On Wed, Jun 19, 2013 at 10:52 AM, Jon Mason wrote: > >> DMA_PRIVATE here keeps all channels private, so they couldn't be used > >> elsewhere, for example raid offload. Do you need a private allocation > >> or can you get away with a dynamically assigned channel? > > > > I would like to have a dedicated DMA engine. async_tx could cause the > > copies to complete out of order. Do I need to add infrastructure to > > allow for private channel usage, and when unused allow the channel to > > be used by async_tx? > > Can NTB just call dma_find_channel() once and be done? Also, async_tx > will only get things out of order if you allow it to pick a new > channel for every operation, but as long as you specify a dependency > chain it will keep things in order (same as remembering the result of > dma_find_channel). Neither of these allow a device exclusive access to a channel. Is this not something that is desired by other users of DMA Engines, or do I have a unique usage model? Thanks, Jon > > -- > Dan -- 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/