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=-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=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 8B82CC2BB9A for ; Tue, 15 Dec 2020 17:13:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 504922251E for ; Tue, 15 Dec 2020 17:13:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730356AbgLORMk (ORCPT ); Tue, 15 Dec 2020 12:12:40 -0500 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:36287 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729462AbgLORKq (ORCPT ); Tue, 15 Dec 2020 12:10:46 -0500 X-Originating-IP: 93.34.118.233 Received: from uno.lan (93-34-118-233.ip49.fastwebnet.it [93.34.118.233]) (Authenticated sender: jacopo@jmondi.org) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id 184601C0008; Tue, 15 Dec 2020 17:10:01 +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 , 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: [PATCH v6 4/5] media: i2c: max9286: Make channel amplitude programmable Date: Tue, 15 Dec 2020 18:09:56 +0100 Message-Id: <20201215170957.92761-5-jacopo+renesas@jmondi.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201215170957.92761-1-jacopo+renesas@jmondi.org> References: <20201215170957.92761-1-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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; + 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 -- 2.29.2