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=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 6BF13C2BBCA for ; Wed, 16 Dec 2020 17:15:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA96B230FA for ; Wed, 16 Dec 2020 17:15:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727011AbgLPRPN (ORCPT ); Wed, 16 Dec 2020 12:15:13 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:42806 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726745AbgLPRPN (ORCPT ); Wed, 16 Dec 2020 12:15:13 -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 5304A2CF; Wed, 16 Dec 2020 18:14:30 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1608138870; bh=lQp49HTuWeMjvxFa2zqwz6oMJLl3H9JlTDtZ44pM+cY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XkaTb6qITxI537hN6t/JnLWql/DUCV+v0LvkoXm2zza7x+8k94Mj3MJQkkblhEVUC BLa2DbsYJgNCHamKu7T4WlHj5AU8VN/uTksS3EhFo5axyjRW7MQuTAqtglBbd4xNNs q7nB2RZ6am6J8BZB5HcCQ2ULltPNubfXqMDH4tmc= Date: Wed, 16 Dec 2020 19:14:23 +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: <20201215170957.92761-5-jacopo+renesas@jmondi.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); 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