Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751663Ab3FZXrI (ORCPT ); Wed, 26 Jun 2013 19:47:08 -0400 Received: from mga09.intel.com ([134.134.136.24]:59413 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843Ab3FZXrG (ORCPT ); Wed, 26 Jun 2013 19:47:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,947,1363158000"; d="scan'208";a="356334171" Date: Wed, 26 Jun 2013 16:47:04 -0700 From: Jon Mason To: Dan Williams Cc: Vinod Koul , Dave Jiang , Linux Kernel Mailing List Subject: Re: [PATCH 1/2] dmadevices: dma_sync_wait undefined Message-ID: <20130626234704.GG3344@jonmason-lab> References: <1371602813-19828-1-git-send-email-jon.mason@intel.com> <1371602813-19828-2-git-send-email-jon.mason@intel.com> <20130619162812.GA20657@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: 1225 Lines: 26 On Thu, Jun 20, 2013 at 02:20:30PM -0700, Dan Williams wrote: > On Wed, Jun 19, 2013 at 9:28 AM, Jon Mason wrote: > > On Tue, Jun 18, 2013 at 06:13:28PM -0700, Dan Williams wrote: > [..] > > NTB is currently using it to flush any pending DMAs. This is needed > > to allow the DMA engine and the CPU to perform operations on the same > > "Memory Window". Without this, it is possible for the operations to > > complete out of order, which is not a desired outcome for any network > > traffic over NTB. CPU is preferred over DMA engine for small > > transfers. Also, it provides an alternative for errors in the DMA > > engine copy process (e.g., DMA mapping, device_prep_dma_memcpy, and > > dmaengine_submit). > > Ok there really isn't a better alternative, is NTB always polling or > does it also use completion callbacks? It uses the callbacks. I've change the code to use dma_find_channel, and will push it for review as a RFC shortly. Thanks, Jon -- 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/