From patchwork Thu Nov 12 16:27:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 11900625 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 9EC841744 for ; Thu, 12 Nov 2020 16:28:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8679122227 for ; Thu, 12 Nov 2020 16:28:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728353AbgKLQ17 (ORCPT ); Thu, 12 Nov 2020 11:27:59 -0500 Received: from relay11.mail.gandi.net ([217.70.178.231]:40429 "EHLO relay11.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728220AbgKLQ17 (ORCPT ); Thu, 12 Nov 2020 11:27:59 -0500 Received: from uno.lan (93-34-118-233.ip49.fastwebnet.it [93.34.118.233]) (Authenticated sender: jacopo@jmondi.org) by relay11.mail.gandi.net (Postfix) with ESMTPSA id C6694100002; Thu, 12 Nov 2020 16:27:52 +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 Subject: [PATCH v4 4/8] media: i2c: max9286: Make channel amplitude programmable Date: Thu, 12 Nov 2020 17:27:25 +0100 Message-Id: <20201112162729.101384-5-jacopo+renesas@jmondi.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201112162729.101384-1-jacopo+renesas@jmondi.org> References: <20201112162729.101384-1-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@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 526b6e557dfb..31e27d0f34f1 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