From patchwork Thu Jun 15 18:30:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 776397 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3wpXCm46dkz9s71 for ; Fri, 16 Jun 2017 04:32:04 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752180AbdFOSa7 (ORCPT ); Thu, 15 Jun 2017 14:30:59 -0400 Received: from sauhun.de ([88.99.104.3]:38218 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753081AbdFOSa4 (ORCPT ); Thu, 15 Jun 2017 14:30:56 -0400 Received: from localhost (p54B338F0.dip0.t-ipconnect.de [84.179.56.240]) by pokefinder.org (Postfix) with ESMTPSA id CE2982C3211; Thu, 15 Jun 2017 20:30:48 +0200 (CEST) From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org, Wolfram Sang , Wolfram Sang Subject: [PATCH 4/4] i2c: rcar: check for DMA-capable buffers Date: Thu, 15 Jun 2017 20:30:39 +0200 Message-Id: <20170615183039.22925-5-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170615183039.22925-1-wsa+renesas@sang-engineering.com> References: <20170615183039.22925-1-wsa+renesas@sang-engineering.com> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Handling this is special for this driver. Because the hardware needs to initialize the next message in interrupt context, we cannot use the i2c_check_msg_for_dma() directly. This helper only works reliably in process context. So, we need to check during initial preparation of the whole transfer and need to disable DMA completely for the whole transfer once a message with a not-DMA-capable buffer is found. Signed-off-by: Wolfram Sang Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-rcar.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 8be3e6cb8fe686..2b679ba4b75066 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -111,8 +111,11 @@ #define ID_ARBLOST (1 << 3) #define ID_NACK (1 << 4) /* persistent flags */ +#define ID_P_NODMA (1 << 30) #define ID_P_PM_BLOCKED (1 << 31) -#define ID_P_MASK ID_P_PM_BLOCKED +#define ID_P_MASK (ID_P_PM_BLOCKED | ID_P_NODMA) + +#define RCAR_DMA_THRESHOLD 8 enum rcar_i2c_type { I2C_RCAR_GEN1, @@ -358,8 +361,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv) unsigned char *buf; int len; - /* Do not use DMA if it's not available or for messages < 8 bytes */ - if (IS_ERR(chan) || msg->len < 8) + if (IS_ERR(chan) || msg->len < RCAR_DMA_THRESHOLD || priv->flags & ID_P_NODMA) return; if (read) { @@ -657,11 +659,15 @@ static void rcar_i2c_request_dma(struct rcar_i2c_priv *priv, struct i2c_msg *msg) { struct device *dev = rcar_i2c_priv_to_dev(priv); - bool read; + bool read = msg->flags & I2C_M_RD; struct dma_chan *chan; enum dma_transfer_direction dir; - read = msg->flags & I2C_M_RD; + /* we need to check here because we need the 'current' context */ + if (i2c_check_msg_for_dma(msg, RCAR_DMA_THRESHOLD, NULL) == -EFAULT) { + dev_dbg(dev, "skipping DMA for this whole transfer\n"); + priv->flags |= ID_P_NODMA; + } chan = read ? priv->dma_rx : priv->dma_tx; if (PTR_ERR(chan) != -EPROBE_DEFER) @@ -740,6 +746,8 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap, if (ret < 0 && ret != -ENXIO) dev_err(dev, "error %d : %x\n", ret, priv->flags); + priv->flags &= ~ID_P_NODMA; + return ret; }