From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 506C87D910 for ; Mon, 11 Feb 2019 15:40:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388028AbfBKPkl (ORCPT ); Mon, 11 Feb 2019 10:40:41 -0500 Received: from ms.lwn.net ([45.79.88.28]:46220 "EHLO ms.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388426AbfBKPkk (ORCPT ); Mon, 11 Feb 2019 10:40:40 -0500 Received: from localhost.localdomain (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id E7E97130D; Mon, 11 Feb 2019 15:40:39 +0000 (UTC) Date: Mon, 11 Feb 2019 08:40:38 -0700 From: Jonathan Corbet To: Federico Vaga Cc: Vinod Koul , , , Subject: Re: [PATCH] doc:dmaengine: clarify DMA desc. pointer after submission Message-ID: <20190211084038.0647430b@lwn.net> In-Reply-To: <20190208153038.23272-1-federico.vaga@cern.ch> References: <20190208153038.23272-1-federico.vaga@cern.ch> Organization: LWN.net X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Fri, 8 Feb 2019 16:30:38 +0100 Federico Vaga wrote: > It clarifies that the DMA description pointer returned by > `dmaengine_prep_*` function should not be used after submission. > > Signed-off-by: Federico Vaga > --- > Documentation/driver-api/dmaengine/client.rst | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst > index fbbb2831f29f..d728e50105eb 100644 > --- a/Documentation/driver-api/dmaengine/client.rst > +++ b/Documentation/driver-api/dmaengine/client.rst > @@ -168,6 +168,13 @@ The details of these operations are: > dmaengine_submit() will not start the DMA operation, it merely adds > it to the pending queue. For this, see step 5, dma_async_issue_pending. > > + .. note:: > + > + After calling ``dmaengine_submit()`` the submitted transfer descriptor > + (``struct dma_async_tx_descriptor``) belongs to the DMA engine. > + Consequentially, the client must consider invalid the pointer to that > + descriptor. > + > 5. Issue pending DMA requests and wait for callback notification > > The transactions in the pending queue can be activated by calling the Applied to the docs tree, thanks. jon