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[PATCH v4 6/6] media: mt9m114: Set pad-slew-rate

Mathis Foerst posted 6 patches 11 months, 1 week ago
There is a newer version of this series
[PATCH v4 6/6] media: mt9m114: Set pad-slew-rate
Posted by Mathis Foerst 11 months, 1 week ago 
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 '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 | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
index 79c97ab19be9..fce24c587782 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;
+	u32 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 & 0xF)
+	      | (sensor->pad_slew_rate & 0xF) << 4
+	      |	(sensor->pad_slew_rate & 0xF) << 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;
@@ -2357,6 +2365,8 @@ 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;
+	u32 slew_rate;
 	int ret;
 
 	ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
@@ -2385,6 +2395,11 @@ static int mt9m114_parse_dt(struct mt9m114 *sensor)
 		goto error;
 	}
 
+	ret = of_property_read_u32(dev_node, "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
Re: [PATCH v4 6/6] media: mt9m114: Set pad-slew-rate
Posted by Laurent Pinchart 9 months, 3 weeks ago 
Hi Mathis,

Thank you for the patch.

On Fri, Mar 07, 2025 at 10:31:40AM +0100, Mathis Foerst wrote:
> 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 '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 | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
> index 79c97ab19be9..fce24c587782 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

You can use decimal values here.

>  #define MT9M114_PAD_CONTROL				CCI_REG16(0x0032)
>  
>  /* XDMA registers */
> @@ -388,6 +391,7 @@ struct mt9m114 {
>  
>  	unsigned int pixrate;
>  	bool streaming;
> +	u32 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 & 0xF)
> +	      | (sensor->pad_slew_rate & 0xF) << 4
> +	      |	(sensor->pad_slew_rate & 0xF) << 8;

No need for ' & 0xF' as you've ensured the slew rate value is in the
valid [0, 7] range.

> +	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;
> @@ -2357,6 +2365,8 @@ 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;
> +	u32 slew_rate;
>  	int ret;
>  
>  	ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
> @@ -2385,6 +2395,11 @@ static int mt9m114_parse_dt(struct mt9m114 *sensor)
>  		goto error;
>  	}
>  
> +	ret = of_property_read_u32(dev_node, "slew-rate", &slew_rate);

Direct usage of OF functions is discouraged. Use
device_property_read_u32() instead, which abstracts the firmware backend
(OF, ACPI, ...). Don't forget to include linux/property.h.

> +	if (ret || slew_rate < MT9M114_PAD_SLEW_MIN || slew_rate > MT9M114_PAD_SLEW_MAX)
> +		slew_rate = MT9M114_PAD_SLEW_DEFAULT;

If the value is erroneous, it indicates the DT is incorrect. I'd log a
message and return an error. As the DT property is optional, you can do
something like

	sensor->slew_rate = MT9M114_PAD_SLEW_DEFAULT;
	device_property_read_u32(&sensor->client.dev, "slew-rate",
				 &sensor->slew_rate);

	if (sensor->slew_rate < MT9M114_PAD_SLEW_MIN ||
	    sensor->slew_rate > MT9M114_PAD_SLEW_MAX) {
	    	dev_err(&sensor->client.dev, "Invalid slew-rate %u\n",
			sensor->slew_rate);
		return -EINVAL;
	}

With this,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> +	sensor->pad_slew_rate = slew_rate;
> +
>  	return 0;
>  
>  error:

-- 
Regards,

Laurent Pinchart

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