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 EFBCBC2BBCD for ; Wed, 16 Dec 2020 17:15:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B83EF23382 for ; Wed, 16 Dec 2020 17:15:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727076AbgLPRPf (ORCPT ); Wed, 16 Dec 2020 12:15:35 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:42822 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726745AbgLPRPf (ORCPT ); Wed, 16 Dec 2020 12:15:35 -0500 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 3DB5445E; Wed, 16 Dec 2020 18:14:52 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1608138892; bh=qi5QC7crOJeytxJKygXG4i2GdQUrkiOb5J7atrBD02M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dxuYPuLK4H9K3Td+F4iqvkJzc8QAdR/MouvbsumkNL+1W2hQ+j0o+JMYPWP1Bmggy OoCX4IAxRDXRE8vCdW6rpiJvjaWZpxARxcJRBJYw3wUU0IgQOlZeTTDGJbauHoCtRr GQaqFRHnxIK4mRdrILiDDLFhybciJjfG9gcEpCvk= Date: Wed, 16 Dec 2020 19:14:45 +0200 From: Laurent Pinchart To: Jacopo Mondi Cc: kieran.bingham+renesas@ideasonboard.com, laurent.pinchart+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org, linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org, Hyun Kwon , Manivannan Sadhasivam , sergei.shtylyov@gmail.com Subject: Re: [PATCH v6 4/5] media: i2c: max9286: Make channel amplitude programmable Message-ID: References: <20201215170957.92761-1-jacopo+renesas@jmondi.org> <20201215170957.92761-5-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 16, 2020 at 07:14:25PM +0200, Laurent Pinchart wrote: > Hi Jacopo, > > Thank you for the patch. > > On Tue, Dec 15, 2020 at 06:09:56PM +0100, Jacopo Mondi wrote: > > Instrument the function that configures the reverse channel with a > > programmable amplitude value. > > > > This change serves to prepare to adjust the reverse channel amplitude > > depending on the remote end high-threshold configuration. > > > > Reviewed-by: Kieran Bingham > > Signed-off-by: Jacopo Mondi > > --- > > drivers/media/i2c/max9286.c | 22 ++++++++++++++++------ > > 1 file changed, 16 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c > > index 1cfc8801c0b2..021309c6dd6f 100644 > > --- a/drivers/media/i2c/max9286.c > > +++ b/drivers/media/i2c/max9286.c > > @@ -336,19 +336,29 @@ static void max9286_configure_i2c(struct max9286_priv *priv, bool localack) > > usleep_range(3000, 5000); > > } > > > > -static void max9286_reverse_channel_setup(struct max9286_priv *priv) > > +static void max9286_reverse_channel_setup(struct max9286_priv *priv, > > + unsigned int chan_amplitude) > > { > > + /* Reverse channel transmission time: default to 1. */ > > + u8 chan_config = MAX9286_REV_TRF(1); > > + > > /* > > * Reverse channel setup. > > * > > * - Enable custom reverse channel configuration (through register 0x3f) > > * and set the first pulse length to 35 clock cycles. > > - * - Increase the reverse channel amplitude to 170mV to accommodate the > > - * high threshold enabled by the serializer driver. > > + * - Adjust reverse channel amplitude: values > 130 are programmed > > + * using the additional +100mV REV_AMP_X boost flag > > */ > > max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35)); > > - max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) | > > - MAX9286_REV_AMP_X); > > + > > + if (chan_amplitude > 100) { > > + /* It is not possible to express values (100 < x < 130) */ > > + chan_amplitude = chan_amplitude < 130 > > + ? 30 : chan_amplitude - 100; > > This could also be written > > chan_amplitude = min(30, chan_amplitude - 100); s/min/max/ of course. > > With or without the change, > > Reviewed-by: Laurent Pinchart > > > + chan_config |= MAX9286_REV_AMP_X; > > + } > > + max9286_write(priv, 0x3b, chan_config | MAX9286_REV_AMP(chan_amplitude)); > > usleep_range(2000, 2500); > > } > > > > @@ -957,7 +967,7 @@ static int max9286_setup(struct max9286_priv *priv) > > * only. This should be disabled after the mux is initialised. > > */ > > max9286_configure_i2c(priv, true); > > - max9286_reverse_channel_setup(priv); > > + max9286_reverse_channel_setup(priv, 170); > > > > /* > > * Enable GMSL links, mask unused ones and autodetect link -- Regards, Laurent Pinchart