Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933398Ab0LUBD6 (ORCPT ); Mon, 20 Dec 2010 20:03:58 -0500 Received: from mail-fx0-f43.google.com ([209.85.161.43]:34599 "EHLO mail-fx0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932881Ab0LUBD5 (ORCPT ); Mon, 20 Dec 2010 20:03:57 -0500 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; b=IueJ2Phq9qMsdvqRdqfIwUofhFrznPBxf9UuHqg021D2VUO8A3lVgb+pq+8bCQ1fgo 6I7SyNCTrzsGIIX1/02ABaWnVTm7M3JdVl/UcKtPZBkdMLN9OA/6uGKejMi/IQzbAJWz 1TzlhCzRw2tYoBm2k2mMgPO20zWY2MpwkiDno= MIME-Version: 1.0 In-Reply-To: References: <1292866298-8585-1-git-send-email-per.forlin@stericsson.com> Date: Mon, 20 Dec 2010 17:03:56 -0800 X-Google-Sender-Auth: ynsdcTU9SeW-BCAM6KEYKWFRgzk Message-ID: Subject: Re: [PATCH] dmaengine: dma40: Add support to split up large elements From: Dan Williams To: Linus Walleij Cc: Per Forlin , linux-kernel@vger.kernel.org, Per Forlin 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: 1335 Lines: 34 On Mon, Dec 20, 2010 at 2:08 PM, Linus Walleij wrote: > 2010/12/20 Per Forlin : > >> The maximum transfer size of the stedma40 is (64k-1) x data-width. >> If the transfer size of one element exceeds this limit >> the job is split up and sent as linked transfer. >> >> Signed-off-by: Per Forlin > > Acked-by: Linus Walleij > > I think this could actually go into 2.6.37 series: I consider it > a bug fix since the transfer size limitation breaks the > contract of the memcpy() API. > If that is the case then the temporary fix for 2.6.37 is along the lines of fixing up the clients to not submit such large requests. You mention the "memcpy api contract" can this be triggered outside of dmatest? The other memcpy clients NET_DMA and ASYNC_TX_DMA will never submit an operation larger than PAGE_SIZE. "4 files changed, 351 insertions(+), 130 deletions(-)" is difficult to defend at this stage of the game, if a smaller "don't do that" patch will suffice for 2.6.37. -- 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/