Hi Francesco,
On 2/18/25 5:56 PM, Francesco Dolcini wrote:
From: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
Add support to configure the PWM-Out pin polarity based on a device
tree property.
Signed-off-by: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
---
drivers/hwmon/amc6821.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/amc6821.c b/drivers/hwmon/amc6821.c
index 1e3c6acd8974..1ea2d97eebca 100644
--- a/drivers/hwmon/amc6821.c
+++ b/drivers/hwmon/amc6821.c
@@ -845,7 +845,7 @@ static int amc6821_detect(struct i2c_client *client, struct i2c_board_info *info
return 0;
}
-static int amc6821_init_client(struct amc6821_data *data)
+static int amc6821_init_client(struct i2c_client *client, struct amc6821_data *data)
{
struct regmap *regmap = data->regmap;
int err;
@@ -864,6 +864,9 @@ static int amc6821_init_client(struct amc6821_data *data)
if (err)
return err;
+ if (of_property_read_bool(client->dev.of_node, "ti,pwm-inverted"))
I know that the AMC6821 is doing a lot of smart things, but this really
tickled me. PWM controllers actually do support that already via
PWM_POLARITY_INVERTED flag for example. See
Documentation/devicetree/bindings/hwmon/adt7475.yaml which seems to be
another HWMON driver which acts as a PWM controller. I'm not sure this
is relevant, applicable or desired but I wanted to highlight this.
+ pwminv = 1;
+
This is silently overriding the module parameter.
I don't think this is a good idea, at the very least not silently.
I would suggest to add some logic in the probe function to set this
value and check its consistency.
Something like:
"""
diff --git a/drivers/hwmon/amc6821.c b/drivers/hwmon/amc6821.c
index 1e3c6acd89740..3a13a914e2bbb 100644
--- a/drivers/hwmon/amc6821.c
+++ b/drivers/hwmon/amc6821.c
@@ -37,7 +37,7 @@ static const unsigned short normal_i2c[] = {0x18,
0x19, 0x1a, 0x2c, 0x2d, 0x2e,
* Insmod parameters
*/
-static int pwminv; /*Inverted PWM output. */
+static int pwminv = -1; /* -1 not modified by the user, 0 default PWM
output, 1 inverted PWM output */
module_param(pwminv, int, 0444);
static int init = 1; /*Power-on initialization.*/
@@ -904,6 +904,7 @@ static int amc6821_probe(struct i2c_client *client)
struct amc6821_data *data;
struct device *hwmon_dev;
struct regmap *regmap;
+ bool pwminv_dt;
int err;
data = devm_kzalloc(dev, sizeof(struct amc6821_data), GFP_KERNEL);
@@ -916,6 +917,18 @@ static int amc6821_probe(struct i2c_client *client)
"Failed to initialize regmap\n");
data->regmap = regmap;
+ pwminv_dt = of_property_read_bool(client->dev.of_node, "ti,pwm-inverted");
+
+ if (pwminv == -1) {
+ pwminv = pwminv_dt;
+ } else if (is_of_node(client->dev.fwnode)) {
+ if ((!pwminv_dt && pwminv) || (pwminv_dt && pwminv == 0)) {
+ dev_err(dev,
+ "Polarity of PWM output passed by module parameter (pwminv=%d)
differs from the one provided through the Device Tree, ignoring Device
Tree value\n",
+ pwminv);
+ }
+ }
+
err = amc6821_init_client(data);
if (err)
return err;
"""
maybe? Note that I have neither compiled nor tested this code.
This also changes the precedence compared to the patch you sent, I think
we may want the module param to override the DT property if there's a
conflict.
What do you think?
Cheers,
Quentin
