From patchwork Thu May 14 17:53:26 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robert Jarzmik X-Patchwork-Id: 6409061 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 93FA89F1CC for ; Thu, 14 May 2015 17:57:56 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C5D5B202DD for ; Thu, 14 May 2015 17:57:55 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 041C720272 for ; Thu, 14 May 2015 17:57:55 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YsxLl-0001kV-1t; Thu, 14 May 2015 17:55:13 +0000 Received: from smtp05.smtpout.orange.fr ([80.12.242.127] helo=smtp.smtpout.orange.fr) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YsxLP-0001ZK-9F for linux-arm-kernel@lists.infradead.org; Thu, 14 May 2015 17:54:52 +0000 Received: from belgarion.home ([92.156.128.44]) by mwinf5d52 with ME id TtuQ1q00N0xcc9003tuXU8; Thu, 14 May 2015 19:54:31 +0200 X-ME-Helo: belgarion.home X-ME-Date: Thu, 14 May 2015 19:54:31 +0200 X-ME-IP: 92.156.128.44 From: Robert Jarzmik To: Vinod Koul , Jonathan Corbet , Daniel Mack , Haojian Zhuang , Robert Jarzmik Subject: [PATCH v3 6/6] Documentation: dmaengine: document DMA_CTRL_ACK Date: Thu, 14 May 2015 19:53:26 +0200 Message-Id: <1431626006-1708-6-git-send-email-robert.jarzmik@free.fr> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1431626006-1708-1-git-send-email-robert.jarzmik@free.fr> References: <1431626006-1708-1-git-send-email-robert.jarzmik@free.fr> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150514_105451_672651_882FC4BB X-CRM114-Status: UNSURE ( 8.62 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -0.0 (/) Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,FREEMAIL_FROM, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add documentation about acking the transfers, and their reusability. Signed-off-by: Robert Jarzmik --- Documentation/dmaengine/provider.txt | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt index 05d2280..33a81ce 100644 --- a/Documentation/dmaengine/provider.txt +++ b/Documentation/dmaengine/provider.txt @@ -345,11 +345,12 @@ where to put them) that abstracts it away. * DMA_CTRL_ACK - - Undocumented feature - - No one really has an idea of what it's about, besides being - related to reusing the DMA transaction descriptors or having - additional transactions added to it in the async-tx API - - Useless in the case of the slave API + - if set, the TX transfer can be reused after being completed. + - there is a guarantee the TX won't be freed until it is acked + by async_tx_ack() + - as a consequence, if a device driver wants to skip the dma_map_sg() and + dma_unmap_sg() because the DMA'd data wasn't used, it can resubmit the + transfer right after its completion. General Design Notes --------------------