From patchwork Thu Oct 15 18:27:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 11839691 X-Patchwork-Delegate: kieran@bingham.xyz Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D00ED1580 for ; Thu, 15 Oct 2020 16:27:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B604022269 for ; Thu, 15 Oct 2020 16:27:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389852AbgJOQ1o (ORCPT ); Thu, 15 Oct 2020 12:27:44 -0400 Received: from relay9-d.mail.gandi.net ([217.70.183.199]:40973 "EHLO relay9-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389798AbgJOQ1n (ORCPT ); Thu, 15 Oct 2020 12:27:43 -0400 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 relay9-d.mail.gandi.net (Postfix) with ESMTPSA id 074E4FF807; Thu, 15 Oct 2020 16:27:39 +0000 (UTC) From: Jacopo Mondi To: kieran.bingham+renesas@ideasonboard.com, laurent.pinchart+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se Cc: Jacopo Mondi , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org, Hyun Kwon , Manivannan Sadhasivam Subject: [PATCH v2 4/7] media: i2c: max9286: Make channel amplitude programmable Date: Thu, 15 Oct 2020 20:27:07 +0200 Message-Id: <20201015182710.54795-5-jacopo+renesas@jmondi.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201015182710.54795-1-jacopo+renesas@jmondi.org> References: <20201015182710.54795-1-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@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. Signed-off-by: Jacopo Mondi Reviewed-by: Kieran Bingham --- 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 89a7248f5c25..163e102199e3 100644 --- a/drivers/media/i2c/max9286.c +++ b/drivers/media/i2c/max9286.c @@ -906,19 +906,29 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv) * Probe/Remove */ -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 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