From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F581C6778C for ; Tue, 3 Jul 2018 12:32:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BE6F2084D for ; Tue, 3 Jul 2018 12:32:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="mxT5pLdE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BE6F2084D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=crapouillou.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932328AbeGCMcq (ORCPT ); Tue, 3 Jul 2018 08:32:46 -0400 Received: from outils.crapouillou.net ([89.234.176.41]:47020 "EHLO crapouillou.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932127AbeGCMcl (ORCPT ); Tue, 3 Jul 2018 08:32:41 -0400 From: Paul Cercueil To: Vinod Koul , Rob Herring , Mark Rutland , Ralf Baechle , Paul Burton , James Hogan , Zubair Lutfullah Kakakhel Cc: Mathieu Malaterre , Daniel Silsby , dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org Subject: [PATCH 10/14] dmaengine: dma-jz4780: Set DTCn register explicitly Date: Tue, 3 Jul 2018 14:32:10 +0200 Message-Id: <20180703123214.23090-11-paul@crapouillou.net> In-Reply-To: <20180703123214.23090-1-paul@crapouillou.net> References: <20180703123214.23090-1-paul@crapouillou.net> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1530621160; bh=Epn573GskJFJvAe4jqYI3koEfREZS0jGyFdeVeplzcQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=mxT5pLdE6yGZotowjGmckqXQbgjpmtGDNEhE1iqbkPtHt/zek5a6Iz/HGe7Zs8askoumTgRmxPtwrxVdRHnG7L078bMyxxGXjjh5OKMBJ/F65cw1dttQS7bxccfq64Ju1LB3mM7k/WeZ9Jazsy/KW0wOuqPkgV1XYfsFJ5Qzzdc= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Silsby Normally, we wouldn't set the channel transfer count register directly when using descriptor-driven transfers. However, there is no harm in doing so, and it allows jz4780_dma_desc_residue() to report the correct residue of an ongoing transfer, no matter when it is called. Signed-off-by: Daniel Silsby --- drivers/dma/dma-jz4780.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c index adada2a3a067..64270d53ba57 100644 --- a/drivers/dma/dma-jz4780.c +++ b/drivers/dma/dma-jz4780.c @@ -526,6 +526,15 @@ static void jz4780_dma_begin(struct jz4780_dma_chan *jzchan) jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DRT, jzchan->transfer_type); + /* + * Set the transfer count. This is redundant for a descriptor-driven + * transfer. However, there can be a delay between the transfer start + * time and when DTCn reg contains the new transfer count. Setting + * it explicitly ensures residue is computed correctly at all times. + */ + jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DTC, + jzchan->desc->desc[jzchan->curr_hwdesc].dtc); + /* Write descriptor address and initiate descriptor fetch. */ desc_phys = jzchan->desc->desc_phys + (jzchan->curr_hwdesc * sizeof(*jzchan->desc->desc)); -- 2.18.0