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@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 22021e9..5336862 100644 (file)
--- 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);
 
        /*