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=-15.8 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,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 48A1DC4332B for ; Tue, 16 Mar 2021 19:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A9AB65069 for ; Tue, 16 Mar 2021 19:25:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240405AbhCPTZE (ORCPT ); Tue, 16 Mar 2021 15:25:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240371AbhCPTYl (ORCPT ); Tue, 16 Mar 2021 15:24:41 -0400 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 89008C06174A; Tue, 16 Mar 2021 12:24:41 -0700 (PDT) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id EED088C8; Tue, 16 Mar 2021 20:24:39 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1615922680; bh=8IOV9swkrnF2YntaMgVClYDlrliiv5d39VZFWxuasgY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ADlB/ful233Uxf4OhdAYcDSV382Z7ChN1L8+YnD9HqIXosdb41veNcIn6x816wfIK N078BmT6lK2ZC6Nobx5juZXZug7iY2kK0nF28TG682+XJfSl6rSIA7f/LKfRMLbzOE 7Yh1Nmx70W8dA2jfkBos+p98VH9y6BfDMUQp6kjU= Date: Tue, 16 Mar 2021 21:24:03 +0200 From: Laurent Pinchart To: Jacopo Mondi Cc: Jacopo Mondi , kieran.bingham+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org, Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 02/18] media: i2c: rdacm20: Enable noise immunity Message-ID: References: <20210315131512.133720-1-jacopo+renesas@jmondi.org> <20210315131512.133720-3-jacopo+renesas@jmondi.org> <20210316125607.lxhrgzahxvxfy6ll@uno.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210316125607.lxhrgzahxvxfy6ll@uno.localdomain> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacopo, On Tue, Mar 16, 2021 at 01:56:07PM +0100, Jacopo Mondi wrote: > On Mon, Mar 15, 2021 at 11:37:26PM +0200, Laurent Pinchart wrote: > > On Mon, Mar 15, 2021 at 02:14:56PM +0100, Jacopo Mondi wrote: > > > 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. > > > > I'm still worried by the race with the MCU. Any update on dumping the > > MCU configuration to check what it initializes ? > > Not yet, you're right ... > > I mainly focused on testing with rdacm21, what if I strip the rdacm20 > changes out from this series ? I will have to keep the init() > operation introduction to maintain compatibility with max9286 changes, > and in case of no regressions, we can keep the 8 seconds delay in the > .dtsi. However it will break upstream support on Eagle for rdacm20 as > we don't have a regulator where to insert the startup delay there, and > a downstream patch that waits for 8 seconds in the deserializer driver > should be used instead... I don't think the rdacm20 changes need to wait. Even this one could be merged as-is, as long as we consider it to be a temporary workaround and don't build anything on top that would make it more difficult to address the issue properly (a TODO comment in the code could help). > > > Reviewed-by: Kieran Bingham > > > 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); > > > } > > > > > > static int rdacm20_probe(struct i2c_client *client) -- Regards, Laurent Pinchart