media: i2c: max9286: Break-out reverse channel setup

Break out the reverse channel setup configuration procedure to its own
function.

This change prepares for configuring the reverse channel conditionally
to the remote side high threshold configuration.

No functional changes intended.
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesasa@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/max9286.c

@@ -336,6 +336,22 @@ 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)
+{
+	/*
+	 * 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.
+	 */
+	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);
+	usleep_range(2000, 2500);
+}
+
 /*
  * max9286_check_video_links() - Make sure video links are detected and locked
  *
@@ -941,19 +957,7 @@ static int max9286_setup(struct max9286_priv *priv)
 	 * only. This should be disabled after the mux is initialised.
 	 */
 	max9286_configure_i2c(priv, true);
-
-	/*
-	 * 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.
-	 */
-	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);
-	usleep_range(2000, 2500);
+	max9286_reverse_channel_setup(priv);
 
 	/*
 	 * Enable GMSL links, mask unused ones and autodetect link