linux-kernel - [PATCH v5 03/15] media: i2c: max9286: Cache channel amplitude

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Date:   Wed, 16 Jun 2021 14:46:04 +0200
From:   Jacopo Mondi <jacopo+renesas@...ndi.org>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        kieran.bingham+renesas@...asonboard.com,
        laurent.pinchart+renesas@...asonboard.com,
        niklas.soderlund+renesas@...natech.se, geert@...ux-m68k.org
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: [PATCH v5 03/15] media: i2c: max9286: Cache channel amplitude

Cache the current channel amplitude in a driver variable
to skip updating it if the newly requested value is the same
as the currently configured one.

Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
---
 drivers/media/i2c/max9286.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 82ec05e96cb7..ed1cdefe7c30 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -165,6 +165,7 @@ struct max9286_priv {
 
 	/* The initial reverse control channel amplitude. */
 	u32 init_rev_chan_mv;
+	u32 rev_chan_mv;
 
 	struct v4l2_ctrl_handler ctrls;
 	struct v4l2_ctrl *pixelrate;
@@ -341,8 +342,15 @@ static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
 static void max9286_reverse_channel_setup(struct max9286_priv *priv,
 					  unsigned int chan_amplitude)
 {
+	u8 chan_config;
+
+	if (priv->rev_chan_mv == chan_amplitude)
+		return;
+
+	priv->rev_chan_mv = chan_amplitude;
+
 	/* Reverse channel transmission time: default to 1. */
-	u8 chan_config = MAX9286_REV_TRF(1);
+	chan_config = MAX9286_REV_TRF(1);
 
 	/*
 	 * Reverse channel setup.
@@ -564,8 +572,7 @@ static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
 	 * - Disable auto-ack as communication on the control channel are now
 	 *   stable.
 	 */
-	if (priv->init_rev_chan_mv < 170)
-		max9286_reverse_channel_setup(priv, 170);
+	max9286_reverse_channel_setup(priv, 170);
 	max9286_check_config_link(priv, priv->source_mask);
 
 	/*
-- 
2.31.1