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

Mathis Foerst
2025-02-26T15:40:10Z

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@mt.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