Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756679Ab0G1XE1 (ORCPT ); Wed, 28 Jul 2010 19:04:27 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:65184 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752373Ab0G1XEO convert rfc822-to-8bit (ORCPT ); Wed, 28 Jul 2010 19:04:14 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=M827Ie66Tk6Zs1kRldWiEQAkGZ81jYmiUqbHHeZXql4CeVjA3KtQ5cBcS73B8/TrKU 3ifzQEbwYGVyoKBjCH0zMyV19nl5ySoKc2ZsodVT+uhGwbf1YBDF7yOKuLX17a73RWMF RxVirqFq8dIWD8zwDIYXco3JosZjw9ppPiN4w= MIME-Version: 1.0 In-Reply-To: References: <1279906072-377-1-git-send-email-linus.walleij@stericsson.com> Date: Thu, 29 Jul 2010 01:04:12 +0200 Message-ID: Subject: Re: [PATCH] DMAENGINE: generic slave channel control v3 From: Linus Walleij To: Dan Williams Cc: linux-kernel@vger.kernel.org, Vinod Koul , Alan Cox 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: 1060 Lines: 27 2010/7/28 Dan Williams : > What are the rules for when a new dma_slave_config can be set? My idea is that these are done immediately before any work to be carried out. > Looking at the driver implementations it seems there is nothing > preventing a concurrent call to device_control to occur at "wrong > time"? ?Is there a synchronization context I'm missing? I do imagine that the code using this will be naturally serialized, since you need to configure the channel before using it for something. i.e. the channel is typically STOPPED. If you like I can add checking for this to the coh901318 and ste_dma40 patches. (It wouldn't affect this one though.) Drivers that want to support reconfiguring while a channel is running a transfer may have to look harder. Yours, Linus Walleij -- 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/