From mboxrd@z Thu Jan 1 00:00:00 1970 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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 CD5DDC433E0 for ; Wed, 17 Feb 2021 12:56:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 956C764E4A for ; Wed, 17 Feb 2021 12:56:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232457AbhBQM4K (ORCPT ); Wed, 17 Feb 2021 07:56:10 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:47566 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231419AbhBQM4F (ORCPT ); Wed, 17 Feb 2021 07:56:05 -0500 Received: from [192.168.0.20] (cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 308EB8C4; Wed, 17 Feb 2021 13:55:22 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1613566522; bh=SZmom8e6Ukq+kensQZ86TKqC3oX7PjE2ZGFbW5sEnbI=; h=Reply-To:Subject:To:Cc:References:From:Date:In-Reply-To:From; b=l7KOgWSOyzPyUPo2F6t44T8fMqWskLMrWg+2CSXSwlDdyNYAJCkz1L6DbTUlbBapI i/3mJJUYg6WJrp4HLNQmOQHHOlvA9VS1+9xvsPzi3qak9Ek1b4PNE2xarSe+MX4Gjo GEPQOaDFPjbmctfKAWh6iGeuUW5AeymcP9TXvq08= Reply-To: kieran.bingham+renesas@ideasonboard.com Subject: Re: [PATCH 01/16] media: i2c: rdacm20: Enable noise immunity To: Jacopo Mondi , laurent.pinchart+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org Cc: Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210216174146.106639-1-jacopo+renesas@jmondi.org> <20210216174146.106639-2-jacopo+renesas@jmondi.org> From: Kieran Bingham Organization: Ideas on Board Message-ID: <5691f68f-724d-9d6a-9ea8-1e017b305c66@ideasonboard.com> Date: Wed, 17 Feb 2021 12:55:19 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210216174146.106639-2-jacopo+renesas@jmondi.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacopo, On 16/02/2021 17:41, Jacopo Mondi wrote: > Enable the noise immunity threshold at the end of the rdacm20 > initialization routine. > > The rdcam20 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. > Oh, this is interesting, ... booting up without the delays would be ... much nicer. > Signed-off-by: Jacopo Mondi > --- > drivers/media/i2c/rdacm20.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c > index 90eb73f0e6e9..f7fd5ae955d0 100644 > --- a/drivers/media/i2c/rdacm20.c > +++ b/drivers/media/i2c/rdacm20.c > @@ -541,7 +541,13 @@ static int rdacm20_initialize(struct rdacm20_device *dev) > > 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. > + */ > + return max9271_set_high_threshold(&dev->serializer, true); Does this work 'out of the box' ? I.e. if this patch is applied, I assume it is required to remove the regulator delays that I/we have in DT? Likewise, does that note mean this patch must also be accompanied by the update in max9286 somehow? I guess we can't keep 'test bisectability' with this very easily so it probably doesn't matter too much, the end result will be the interesting part. Reviewed-by: Kieran Bingham > } > > static int rdacm20_probe(struct i2c_client *client) >