From patchwork Fri Mar 19 16:41:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 12151487 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 D2D57C433C1 for ; Fri, 19 Mar 2021 16:43:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A17896197D for ; Fri, 19 Mar 2021 16:43:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230300AbhCSQms (ORCPT ); Fri, 19 Mar 2021 12:42:48 -0400 Received: from relay6-d.mail.gandi.net ([217.70.183.198]:36899 "EHLO relay6-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230253AbhCSQmR (ORCPT ); Fri, 19 Mar 2021 12:42:17 -0400 X-Originating-IP: 5.92.35.220 Received: from uno.localdomain (mob-5-92-35-220.net.vodafone.it [5.92.35.220]) (Authenticated sender: jacopo@jmondi.org) by relay6-d.mail.gandi.net (Postfix) with ESMTPSA id 4DCF9C0007; Fri, 19 Mar 2021 16:42:13 +0000 (UTC) From: Jacopo Mondi To: kieran.bingham+renesas@ideasonboard.com, laurent.pinchart+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org Cc: Jacopo Mondi , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 14/19] media: i2c: rdacm20: Enable noise immunity Date: Fri, 19 Mar 2021 17:41:43 +0100 Message-Id: <20210319164148.199192-15-jacopo+renesas@jmondi.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210319164148.199192-1-jacopo+renesas@jmondi.org> References: <20210319164148.199192-1-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Enable the noise immunity threshold at the end of the rdacm20 initialization routine. The rdacm20 camera module has been so far tested with a startup delay that allowed the embedded MCU to program the serializer. If the initialization routine is run before the MCU programs the serializer and the image sensor and their addresses gets changed by the rdacm20 driver it is required to manually enable the noise immunity threshold to make the communication on the control channel more reliable. Reviewed-by: Kieran Bingham Signed-off-by: Jacopo Mondi Reviewed-by: Laurent Pinchart --- drivers/media/i2c/rdacm20.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c index 2881e752efbe..554fd3b3ec3d 100644 --- a/drivers/media/i2c/rdacm20.c +++ b/drivers/media/i2c/rdacm20.c @@ -518,7 +518,19 @@ static int rdacm20_init(struct v4l2_subdev *sd, unsigned int val) dev_info(dev->dev, "Identified MAX9271 + OV10635 device\n"); - return 0; + /* + * Set reverse channel high threshold to increase noise immunity. + * + * This should be compensated by increasing the reverse channel + * amplitude on the remote deserializer side. + * + * TODO Inspect the embedded MCU programming sequence to make sure + * there are no conflicts with the configuration applied here. + * + * TODO Clarify the embedded MCU startup delay to avoid write + * collisions on the I2C bus. + */ + return max9271_set_high_threshold(&dev->serializer, true); } static const struct v4l2_subdev_core_ops rdacm20_core_ops = {