From patchwork Tue Feb 21 17:10:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 13148232 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BF8CC636D7 for ; Tue, 21 Feb 2023 17:11:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234265AbjBURLd (ORCPT ); Tue, 21 Feb 2023 12:11:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234598AbjBURLb (ORCPT ); Tue, 21 Feb 2023 12:11:31 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1F9216321 for ; Tue, 21 Feb 2023 09:11:26 -0800 (PST) Received: from uno.homenet.telecomitalia.it (host-87-16-53-160.retail.telecomitalia.it [87.16.53.160]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 305EC6E0; Tue, 21 Feb 2023 18:11:11 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1676999471; bh=J94INdMsM4g8iTa+KyiNHUaPiuzZHbLQb6cGRS6bfAQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dlzuOY5YFrnTJWcKtggK5niVlBFadu7TPQtJOe4vOrVYAs2AW6hPXI+D5nC5s5u+7 2ikRW3ej+b475gqXRLcNGgUpTV1LR9QMuLVlsunZMKKV56If/NZQ/90zJOlT1LQJ9W QJPpElnljZIaWwWORXjIcTh6X359tEQyttHUPFJE= From: Jacopo Mondi To: Mikhail Rudenko , Dave Stevenson , Laurent Pinchart , Sakari Ailus Cc: Jacopo Mondi , linux-media@vger.kernel.org, Tommaso Merciai Subject: [PATCH v2 2/2] media: i2c: ov5647: Use bus-locked i2c_transfer() Date: Tue, 21 Feb 2023 18:10:48 +0100 Message-Id: <20230221171048.203042-3-jacopo.mondi@ideasonboard.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230221171048.203042-1-jacopo.mondi@ideasonboard.com> References: <20230221171048.203042-1-jacopo.mondi@ideasonboard.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org The ov5647_read() functions calls i2c_master_send() and i2c_master_read() in sequence. However this leaves space for other clients to contend the bus and insert an unrelated transaction in between the two calls. Replace the two calls with a single i2c_transfer() one, that locks the bus in between the transactions. Signed-off-by: Jacopo Mondi Reviewed-by: Tommaso Merciai Reviewed-by: Dave Stevenson Reviewed-by: Laurent Pinchart Reviewed-by: Laurent Pinchart --- drivers/media/i2c/ov5647.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c index bde287e00c87..ca7079bb7589 100644 --- a/drivers/media/i2c/ov5647.c +++ b/drivers/media/i2c/ov5647.c @@ -629,23 +629,29 @@ static int ov5647_write(struct v4l2_subdev *sd, u16 reg, u8 val) static int ov5647_read(struct v4l2_subdev *sd, u16 reg, u8 *val) { - unsigned char data_w[2] = { reg >> 8, reg & 0xff }; struct i2c_client *client = v4l2_get_subdevdata(sd); + u8 buf[2] = { reg >> 8, reg & 0xff }; + struct i2c_msg msg[2]; int ret; - ret = i2c_master_send(client, data_w, 2); - if (ret < 0) { - dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n", - __func__, reg); - return ret; + msg[0].addr = client->addr; + msg[0].flags = client->flags; + msg[0].buf = buf; + msg[0].len = sizeof(buf); + + msg[1].addr = client->addr; + msg[1].flags = client->flags | I2C_M_RD; + msg[1].buf = buf; + msg[1].len = 1; + + ret = i2c_transfer(client->adapter, msg, 2); + if (ret != 2) { + dev_err(&client->dev, "%s: i2c read error, reg: %x = %d\n", + __func__, reg, ret); + return ret >= 0 ? -EINVAL : ret; } - ret = i2c_master_recv(client, val, 1); - if (ret < 0) { - dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n", - __func__, reg); - return ret; - } + *val = buf[0]; return 0; }