Re: [PATCH v5 106/111] staging: greybus: pwm: Make use of devm_pwmchip_alloc() function

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On 1/25/24 6:10 AM, Uwe Kleine-König wrote:
This prepares the greybus pwm driver to further changes of the pwm core
outlined in the commit introducing devm_pwmchip_alloc(). There is no
intended semantical change and the driver should behave as before.

Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>

I think you are changing more than you need to in this code.

---
  drivers/staging/greybus/pwm.c | 75 ++++++++++-------------------------
  1 file changed, 20 insertions(+), 55 deletions(-)

diff --git a/drivers/staging/greybus/pwm.c b/drivers/staging/greybus/pwm.c
index 75e0518791d8..a90f41c374dc 100644
--- a/drivers/staging/greybus/pwm.c
+++ b/drivers/staging/greybus/pwm.c
@@ -16,26 +16,11 @@
struct gb_pwm_chip {
  	struct gb_connection	*connection;
-	u8			pwm_max;	/* max pwm number */
-	struct pwm_chip		chip;
  };
static inline struct gb_pwm_chip *pwm_chip_to_gb_pwm_chip(struct pwm_chip *chip)
  {
-	return container_of(chip, struct gb_pwm_chip, chip);

Now I understand why you were changing the type of the argument
passed to all those functions.  I still don't think you need
to do that though.

-}
-
-static int gb_pwm_count_operation(struct gb_pwm_chip *pwmc)

This function logically isolates doing the operation from
the rest of the code.  I'd rather you not get rid of it.

-{
-	struct gb_pwm_count_response response;
-	int ret;
-
-	ret = gb_operation_sync(pwmc->connection, GB_PWM_TYPE_PWM_COUNT,
-				NULL, 0, &response, sizeof(response));
-	if (ret)
-		return ret;
-	pwmc->pwm_max = response.count;
-	return 0;
+	return pwmchip_get_drvdata(chip);
  }
static int gb_pwm_activate_operation(struct pwm_chip *chip, u8 which)
@@ -45,9 +30,6 @@ static int gb_pwm_activate_operation(struct pwm_chip *chip, u8 which)
  	struct gbphy_device *gbphy_dev;
  	int ret;
- if (which > pwmc->pwm_max)
-		return -EINVAL;
-
  	request.which = which;
gbphy_dev = to_gbphy_dev(pwmchip_parent(chip));
@@ -71,9 +53,6 @@ static int gb_pwm_deactivate_operation(struct pwm_chip *chip,
  	struct gbphy_device *gbphy_dev;
  	int ret;
- if (which > pwmc->pwm_max)
-		return -EINVAL;
-
  	request.which = which;
gbphy_dev = to_gbphy_dev(pwmchip_parent(chip));
@@ -97,9 +76,6 @@ static int gb_pwm_config_operation(struct pwm_chip *chip,
  	struct gbphy_device *gbphy_dev;
  	int ret;
- if (which > pwmc->pwm_max)
-		return -EINVAL;
-
  	request.which = which;
  	request.duty = cpu_to_le32(duty);
  	request.period = cpu_to_le32(period);
@@ -125,9 +101,6 @@ static int gb_pwm_set_polarity_operation(struct pwm_chip *chip,
  	struct gbphy_device *gbphy_dev;
  	int ret;
- if (which > pwmc->pwm_max)
-		return -EINVAL;
-
  	request.which = which;
  	request.polarity = polarity;
@@ -151,9 +124,6 @@ static int gb_pwm_enable_operation(struct pwm_chip *chip, u8 which)
  	struct gbphy_device *gbphy_dev;
  	int ret;
- if (which > pwmc->pwm_max)
-		return -EINVAL;
-
  	request.which = which;
gbphy_dev = to_gbphy_dev(pwmchip_parent(chip));
@@ -176,9 +146,6 @@ static int gb_pwm_disable_operation(struct pwm_chip *chip, u8 which)
  	struct gbphy_device *gbphy_dev;
  	int ret;
- if (which > pwmc->pwm_max)
-		return -EINVAL;
-
  	request.which = which;
ret = gb_operation_sync(pwmc->connection, GB_PWM_TYPE_DISABLE,
@@ -263,38 +230,37 @@ static int gb_pwm_probe(struct gbphy_device *gbphy_dev,
  	struct gb_connection *connection;
  	struct gb_pwm_chip *pwmc;
  	struct pwm_chip *chip;
+	struct gb_pwm_count_response response;
  	int ret;
- pwmc = kzalloc(sizeof(*pwmc), GFP_KERNEL);
-	if (!pwmc)
-		return -ENOMEM;
-
  	connection = gb_connection_create(gbphy_dev->bundle,
  					  le16_to_cpu(gbphy_dev->cport_desc->id),
  					  NULL);
-	if (IS_ERR(connection)) {
-		ret = PTR_ERR(connection);
-		goto exit_pwmc_free;
+	if (IS_ERR(connection))
+		return PTR_ERR(connection);

This is actually a bug fix that should probably be done
separately, prior to this series.

+
+	ret = gb_operation_sync(pwmc->connection, GB_PWM_TYPE_PWM_COUNT,
+				NULL, 0, &response, sizeof(response));
+	if (ret)
+		goto exit_connection_destroy;

You didn't mention in your header that you were getting rid
of gb_pwm_count_operation(), and as I said above, I don't
think you should.  Just keep the existing code as it was
and focus only on your conversion to attaching driver data
to the PWM chip structure.

+
+	chip = devm_pwmchip_alloc(&gbphy_dev->dev, response.count, sizeof(*pwmc));
+	if (IS_ERR(chip)) {
+		ret = PTR_ERR(chip);
+		goto exit_connection_destroy;
  	}
+ pwmc = pwm_chip_to_gb_pwm_chip(chip);
  	pwmc->connection = connection;
+
  	gb_connection_set_data(connection, pwmc);
-	gb_gbphy_set_data(gbphy_dev, pwmc);
+	gb_gbphy_set_data(gbphy_dev, chip);

I'm pretty sure driver data should still be the Greybus
structure, otherwise you're really changing the way this
works (most likely in a way that's different from other
Greybus drivers.

ret = gb_connection_enable(connection);
  	if (ret)
  		goto exit_connection_destroy;
- /* Query number of pwms present */
-	ret = gb_pwm_count_operation(pwmc);
-	if (ret)
-		goto exit_connection_disable;
-
-	chip = &pwmc->chip;
-
-	chip->dev = &gbphy_dev->dev;
  	chip->ops = &gb_pwm_ops;
-	chip->npwm = pwmc->pwm_max + 1;
ret = pwmchip_add(chip);
  	if (ret) {
@@ -310,14 +276,13 @@ static int gb_pwm_probe(struct gbphy_device *gbphy_dev,
  	gb_connection_disable(connection);
  exit_connection_destroy:
  	gb_connection_destroy(connection);
-exit_pwmc_free:
-	kfree(pwmc);
  	return ret;
  }
static void gb_pwm_remove(struct gbphy_device *gbphy_dev)
  {
-	struct gb_pwm_chip *pwmc = gb_gbphy_get_data(gbphy_dev);
+	struct pwm_chip *chip = gb_gbphy_get_data(gbphy_dev);
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
  	struct gb_connection *connection = pwmc->connection;
  	int ret;
@@ -325,7 +290,7 @@ static void gb_pwm_remove(struct gbphy_device *gbphy_dev)
  	if (ret)
  		gbphy_runtime_get_noresume(gbphy_dev);
- pwmchip_remove(&pwmc->chip);
+	pwmchip_remove(chip);
  	gb_connection_disable(connection);
  	gb_connection_destroy(connection);
  	kfree(pwmc);





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