linux-kernel - [PATCH v1 8/8] MT9M114: Set pad-slew-rate

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Message-Id: <20250226153929.274562-9-mathis.foerst@mt.com>
Date: Wed, 26 Feb 2025 16:39:29 +0100
From: Mathis Foerst <mathis.foerst@...com>
To: linux-kernel@...r.kernel.org
Cc: Mathis Foerst <mathis.foerst@...com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	linux-media@...r.kernel.org,
	devicetree@...r.kernel.org,
	manuel.traut@...com
Subject: [PATCH v1 8/8] MT9M114: Set pad-slew-rate

The MT9M114 supports the different slew rates (0 to 7) on the output pads.
At the moment, this is hardcoded to 7 (the fastest rate).
The user might want to change this values due to EMC requirements.

Read the 'pad-slew-rate' from the DT and configure the pad slew rates of
the output pads accordingly in mt9m114_initialize().
Remove the hardcoded slew rate setting from the mt9m114_init table.

Signed-off-by: Mathis Foerst <mathis.foerst@...com>
---
 drivers/media/i2c/mt9m114.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
index f96f6c010e1b..327384e8427d 100644
--- a/drivers/media/i2c/mt9m114.c
+++ b/drivers/media/i2c/mt9m114.c
@@ -42,6 +42,9 @@
 #define MT9M114_RESET_AND_MISC_CONTROL			CCI_REG16(0x001a)
 #define MT9M114_RESET_SOC					BIT(0)
 #define MT9M114_PAD_SLEW				CCI_REG16(0x001e)
+#define MT9M114_PAD_SLEW_MIN					0x00
+#define MT9M114_PAD_SLEW_MAX					0x07
+#define MT9M114_PAD_SLEW_DEFAULT				0x07
 #define MT9M114_PAD_CONTROL				CCI_REG16(0x0032)
 
 /* XDMA registers */
@@ -388,6 +391,7 @@ struct mt9m114 {
 
 	unsigned int pixrate;
 	bool streaming;
+	u8 pad_slew_rate;
 
 	/* Pixel Array */
 	struct {
@@ -645,9 +649,6 @@ static const struct cci_reg_sequence mt9m114_init[] = {
 	{ MT9M114_CAM_SENSOR_CFG_FINE_INTEG_TIME_MAX,	1459 },
 	{ MT9M114_CAM_SENSOR_CFG_FINE_CORRECTION,	96 },
 	{ MT9M114_CAM_SENSOR_CFG_REG_0_DATA,		32 },
-
-	/* Miscellaneous settings */
-	{ MT9M114_PAD_SLEW,				0x0777 },
 };
 
 /* -----------------------------------------------------------------------------
@@ -778,6 +779,13 @@ static int mt9m114_initialize(struct mt9m114 *sensor)
 	if (ret < 0)
 		return ret;
 
+	value = sensor->pad_slew_rate |
+		sensor->pad_slew_rate << 4 |
+		sensor->pad_slew_rate << 8;
+	cci_write(sensor->regmap, MT9M114_PAD_SLEW, value, &ret);
+	if (ret < 0)
+		return ret;
+
 	ret = mt9m114_set_state(sensor, MT9M114_SYS_STATE_ENTER_CONFIG_CHANGE);
 	if (ret < 0)
 		return ret;
@@ -2363,6 +2371,7 @@ static int mt9m114_parse_dt(struct mt9m114 *sensor)
 	struct fwnode_handle *fwnode = dev_fwnode(&sensor->client->dev);
 	struct fwnode_handle *ep;
 	struct device_node *dev_node = sensor->client->dev.of_node;
+	u8 slew_rate;
 	int ret;
 
 	ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
@@ -2393,6 +2402,11 @@ static int mt9m114_parse_dt(struct mt9m114 *sensor)
 
 	sensor->bypass_pll = of_property_read_bool(dev_node, "bypass-pll");
 
+	ret = of_property_read_u8(dev_node, "pad-slew-rate", &slew_rate);
+	if (ret || slew_rate < MT9M114_PAD_SLEW_MIN || slew_rate > MT9M114_PAD_SLEW_MAX)
+		slew_rate = MT9M114_PAD_SLEW_DEFAULT;
+	sensor->pad_slew_rate = slew_rate;
+
 	return 0;
 
 error:
-- 
2.34.1