From patchwork Tue Jul 3 12:32:10 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 10503991 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0BF5F6035E for ; Tue, 3 Jul 2018 12:40:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ED9BC287C6 for ; Tue, 3 Jul 2018 12:40:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E196E288CD; Tue, 3 Jul 2018 12:40:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 91742287C6 for ; Tue, 3 Jul 2018 12:40:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753429AbeGCMky (ORCPT ); Tue, 3 Jul 2018 08:40:54 -0400 Received: from outils.crapouillou.net ([89.234.176.41]:57872 "EHLO crapouillou.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753404AbeGCMko (ORCPT ); Tue, 3 Jul 2018 08:40:44 -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: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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));