From patchwork Wed May 23 09:56:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Esben Haabendal X-Patchwork-Id: 918926 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-i2c-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="FB3xXFe/"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40rSct3rskz9s0y for ; Wed, 23 May 2018 19:58:06 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932264AbeEWJ6E (ORCPT ); Wed, 23 May 2018 05:58:04 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:35007 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932291AbeEWJ4c (ORCPT ); Wed, 23 May 2018 05:56:32 -0400 Received: by mail-wm0-f67.google.com with SMTP id o78-v6so7530355wmg.0; Wed, 23 May 2018 02:56:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=m5atjfdioKpL9uRdAJ0UDf7EcIvoU736qRqVqPZ+w/8=; b=FB3xXFe/SXrvnM49koGqdOSfienhw+gjl0PR6hvvIUT/kxdwhLLXIUTSPFkotsvWQt oZ+ySQdU4PZQyxWSEtkIknWS4MJWIJ81dmZUUhbi8RgvDVSF/YVwMPMep8Swddg1w6So +svn5BIVfSckJWuRT33wOgykZboh8hClCckLw2l2O79YfYknN+A1q1MHRUkvHcazfD8s +M/xlpdZfcP67Zy0IV+DEorAfGcXw6Tz6XHLV97fv8m6A5MN1B21UH9whc5jRNucFTQ1 KwDc2uqmjB6q5jXP775PRTNWPtHpoPQp8A75eMftRplkB5Dvx58e1j39ooWCUIX+myO7 I/pw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; bh=m5atjfdioKpL9uRdAJ0UDf7EcIvoU736qRqVqPZ+w/8=; b=WTqoj04IFDkoKcag4mW/VeHSXRE6ucqOoqKihFX0y2d8Xgl4yVAityAWp0XE2m4EmR gAYl/snucFnVxo+4Z4Xj+VeIcLoGX9gBBICnu1Qld0zNkWi5oA30QwAGoWp9vuthzkzN AszDkD6+esAy599gZZfYJk2XUhAdTCMvZ3Oo1ZxPUQNV4EWZ4KRS6m+8tfIipKROInz9 RWNG3fnjDbkfnc+klgjMImsWptypR3xXUQAI4O3bIkPPqW4WPuFu930xVCl6xGiLxWVz e4uB2uYUd/JuorU6DH+Kv4DGahybRaV7bSycsKU06fTBreF+54PBKYobDX3pUwshsm0E 317w== X-Gm-Message-State: ALKqPwf+AVGXg3mueeiUbBEMsFWMyZE/bvEOm6fVLpKQWVCLM2OBYD1I 2oc/jZOBUvo5VMIU9fwaE5VutFHvHdU= X-Google-Smtp-Source: AB8JxZqXi1VWW9H4zbb1DXxmMgCv+9hlrqqoHJL4//jcT6xL1oOLhuNcfz+E6RIBWPtHFMvsKz2abQ== X-Received: by 2002:a2e:86d9:: with SMTP id n25-v6mr1346975ljj.18.1527069391082; Wed, 23 May 2018 02:56:31 -0700 (PDT) Received: from localhost ([87.54.42.112]) by smtp.gmail.com with ESMTPSA id e9-v6sm3415417ljg.90.2018.05.23.02.56.30 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 23 May 2018 02:56:30 -0700 (PDT) From: Esben Haabendal To: linux-i2c@vger.kernel.org Cc: Esben Haabendal , Wolfram Sang , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Lucas Stach , Phil Reid , Linus Walleij , Clemens Gruber , Wei Jinhua , Michail Georgios Etairidis , linux-kernel@vger.kernel.org Subject: [PATCH 2/4] i2c: imx: Fix race condition in dma read Date: Wed, 23 May 2018 11:56:21 +0200 Message-Id: <20180523095623.3347-3-esben.haabendal@gmail.com> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180523095623.3347-1-esben.haabendal@gmail.com> References: <20180523095623.3347-1-esben.haabendal@gmail.com> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org From: Esben Haabendal This fixes a race condition, where the DMAEN bit ends up being set after I2C slave has transmitted a byte following the dummy read. When that happens, an interrupt is generated instead, and no DMA request is generated to kickstart the DMA read, and a timeout happens after DMA_TIMEOUT (1 sec). Fixed by setting the DMAEN bit before the dummy read. Signed-off-by: Esben Haabendal --- drivers/i2c/busses/i2c-imx.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 6fca5e64cffb..742b548437af 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -677,9 +677,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, struct imx_i2c_dma *dma = i2c_imx->dma; struct device *dev = &i2c_imx->adapter.dev; - temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); - temp |= I2CR_DMAEN; - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); dma->chan_using = dma->chan_rx; dma->dma_transfer_dir = DMA_DEV_TO_MEM; @@ -819,6 +816,11 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo if ((msgs->len - 1) || block_data) temp &= ~I2CR_TXAK; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data) { + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp |= I2CR_DMAEN; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + } imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */ dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);