Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757948Ab3FTVUd (ORCPT ); Thu, 20 Jun 2013 17:20:33 -0400 Received: from mail-la0-f52.google.com ([209.85.215.52]:33370 "EHLO mail-la0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757710Ab3FTVUc (ORCPT ); Thu, 20 Jun 2013 17:20:32 -0400 MIME-Version: 1.0 In-Reply-To: <20130619162812.GA20657@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> Date: Thu, 20 Jun 2013 14:20:30 -0700 X-Google-Sender-Auth: Hopf0fQJljvft02EJsrkkh6GduI Message-ID: Subject: Re: [PATCH 1/2] dmadevices: dma_sync_wait undefined From: Dan Williams To: Jon Mason Cc: Vinod Koul , Dave Jiang , Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1005 Lines: 19 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? -- 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/