Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754061AbZGBA6T (ORCPT ); Wed, 1 Jul 2009 20:58:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752475AbZGBA6J (ORCPT ); Wed, 1 Jul 2009 20:58:09 -0400 Received: from mail-vw0-f202.google.com ([209.85.212.202]:48954 "EHLO mail-vw0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750969AbZGBA6I convert rfc822-to-8bit (ORCPT ); Wed, 1 Jul 2009 20:58:08 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=btO6+TBsD8KL9nEgwx+ScU64+vfFvo02Y6Xy7+k+C8uzm5bs2aKy1lSmTQTW+ILxWi jXZ+OPwbxtpWXmz5HXygoSZtmw8UxqaXGUH3cjVhpgXnNknaQscmZgQpPXIWvb5uotZf B8xgaM13wmOtnhJ1rVw0U1GjsYHs0YfwW75k4= MIME-Version: 1.0 In-Reply-To: <4A4B6B90.90006@atmel.com> References: <1246012936-10812-1-git-send-email-nicolas.ferre@atmel.com> <4A4B6B90.90006@atmel.com> Date: Wed, 1 Jul 2009 17:58:10 -0700 X-Google-Sender-Auth: 60e30f4441f963d7 Message-ID: Subject: Re: [PATCH 1/2 v2] dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller From: Dan Williams To: Nicolas Ferre Cc: maciej.sosnowski@intel.com, avictor.za@gmail.com, linux-arm-kernel@lists.arm.linux.org.uk, patrice.vilchez@atmel.com, linux-kernel@vger.kernel.org, Atsushi Nemoto Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1438 Lines: 40 On Wed, Jul 1, 2009 at 6:58 AM, Nicolas Ferre wrote: > Hi, > > Just one question Dan (see below). > > Nicolas Ferre : >> This AHB DMA Controller (aka HDMA or DMAC on AT91 systems) is availlable on >> at91sam9rl chip. It will be used on other products in the future. > > [..] >> + ? ? /* >> + ? ? ?* The API requires that no submissions are done from a >> + ? ? ?* callback, so we don't need to drop the lock here >> + ? ? ?*/ >> + ? ? if (callback) >> + ? ? ? ? ? ? callback(param); > > Even if our dma controller does not seems to take advantage of > dependency requests... > > ...should I add the > dma_run_dependencies(txd); > call here to improve conformance to dmaengine standards ? That would be nice but it is not a strict requirement. To me it just seems like leaving something for some future developer to trip over when debugging why channel switching does not work with this driver. If you can guarantee that this driver will always be the only dma_device driver in the system and that future products will not add additional operation types then maybe it can be omitted. Otherwise, the overhead of including the call should be negligible. Regards, 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/