[PATCH v3 0/2] backlight: lm3630a: convert to atomic PWM API

From: Uwe Kleine-König <redacted>

Hello,

this is v3 of the series. In v1 and v2 I failed to notice that the
driver contains two (nearly identical) update_status callbacks. Daniel
pointed that out, so here comes v3.

Best regards
Uwe

Uwe Kleine-König (2):
  backlight: lm3630a: fix return code of .update_status() callback
  backlight: lm3630a: convert to atomic PWM API and check for errors

 drivers/video/backlight/lm3630a_bl.c | 50 +++++++++++++---------------
 1 file changed, 23 insertions(+), 27 deletions(-)

-- 
2.30.2

The practical upside here is that this only needs a single API call to
program the hardware which (depending on the underlaying hardware) can
be more effective and prevents glitches.

Up to now the return value of the pwm functions was ignored. Fix this
and propagate the error to the caller.

Signed-off-by: Uwe Kleine-König <redacted>
---
 drivers/video/backlight/lm3630a_bl.c | 42 +++++++++++++---------------
 1 file changed, 19 insertions(+), 23 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index 7140b0d98082..f377dfdd9868 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c

@@ -52,6 +52,7 @@ struct lm3630a_chip {
 	struct gpio_desc *enable_gpio;
 	struct regmap *regmap;
 	struct pwm_device *pwmd;
+	struct pwm_state pwmd_state;
 };
 
 /* i2c access */

@@ -167,16 +168,19 @@ static int lm3630a_intr_config(struct lm3630a_chip *pchip)
 	return rval;
 }
 
-static void lm3630a_pwm_ctrl(struct lm3630a_chip *pchip, int br, int br_max)
+static int lm3630a_pwm_ctrl(struct lm3630a_chip *pchip, int br, int br_max)
 {
-	unsigned int period = pchip->pdata->pwm_period;
-	unsigned int duty = br * period / br_max;
+	int err;
 
-	pwm_config(pchip->pwmd, duty, period);
-	if (duty)
-		pwm_enable(pchip->pwmd);
-	else
-		pwm_disable(pchip->pwmd);
+	pchip->pwmd_state.period = pchip->pdata->pwm_period;
+
+	err = pwm_set_relative_duty_cycle(&pchip->pwmd_state, br, br_max);
+	if (err)
+		return err;
+
+	pchip->pwmd_state.enabled = pchip->pwmd_state.duty_cycle ? true : false;
+
+	return pwm_apply_state(pchip->pwmd, &pchip->pwmd_state);
 }
 
 /* update and get brightness */

@@ -187,11 +191,9 @@ static int lm3630a_bank_a_update_status(struct backlight_device *bl)
 	enum lm3630a_pwm_ctrl pwm_ctrl = pchip->pdata->pwm_ctrl;
 
 	/* pwm control */
-	if ((pwm_ctrl & LM3630A_PWM_BANK_A) != 0) {
-		lm3630a_pwm_ctrl(pchip, bl->props.brightness,
-				 bl->props.max_brightness);
-		return 0;
-	}
+	if ((pwm_ctrl & LM3630A_PWM_BANK_A) != 0)
+		return lm3630a_pwm_ctrl(pchip, bl->props.brightness,
+					bl->props.max_brightness);
 
 	/* disable sleep */
 	ret = lm3630a_update(pchip, REG_CTRL, 0x80, 0x00);

@@ -264,11 +266,9 @@ static int lm3630a_bank_b_update_status(struct backlight_device *bl)
 	enum lm3630a_pwm_ctrl pwm_ctrl = pchip->pdata->pwm_ctrl;
 
 	/* pwm control */
-	if ((pwm_ctrl & LM3630A_PWM_BANK_B) != 0) {
-		lm3630a_pwm_ctrl(pchip, bl->props.brightness,
-				 bl->props.max_brightness);
-		return 0;
-	}
+	if ((pwm_ctrl & LM3630A_PWM_BANK_B) != 0)
+		return lm3630a_pwm_ctrl(pchip, bl->props.brightness,
+					bl->props.max_brightness);
 
 	/* disable sleep */
 	ret = lm3630a_update(pchip, REG_CTRL, 0x80, 0x00);

@@ -563,11 +563,7 @@ static int lm3630a_probe(struct i2c_client *client,
 			return PTR_ERR(pchip->pwmd);
 		}
 
-		/*
-		 * FIXME: pwm_apply_args() should be removed when switching to
-		 * the atomic PWM API.
-		 */
-		pwm_apply_args(pchip->pwmd);
+		pwm_init_state(pchip->pwmd, &pchip->pwmd_state);
 	}
 
 	/* interrupt enable  : irq 0 is not allowed */

-- 
2.30.2

According to <linux/backlight.h> .update_status() is supposed to
return 0 on success and a negative error code otherwise. Adapt
lm3630a_bank_a_update_status() and lm3630a_bank_b_update_status() to
actually do it.

While touching that also add the error code to the failure message.

Signed-off-by: Uwe Kleine-König <redacted>
---
 drivers/video/backlight/lm3630a_bl.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index e88a2b0e5904..7140b0d98082 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c

@@ -190,7 +190,7 @@ static int lm3630a_bank_a_update_status(struct backlight_device *bl)
 	if ((pwm_ctrl & LM3630A_PWM_BANK_A) != 0) {
 		lm3630a_pwm_ctrl(pchip, bl->props.brightness,
 				 bl->props.max_brightness);
-		return bl->props.brightness;
+		return 0;
 	}
 
 	/* disable sleep */

@@ -210,8 +210,8 @@ static int lm3630a_bank_a_update_status(struct backlight_device *bl)
 	return 0;
 
 out_i2c_err:
-	dev_err(pchip->dev, "i2c failed to access\n");
-	return bl->props.brightness;
+	dev_err(pchip->dev, "i2c failed to access (%pe)\n", ERR_PTR(ret));
+	return ret;
 }
 
 static int lm3630a_bank_a_get_brightness(struct backlight_device *bl)

@@ -267,7 +267,7 @@ static int lm3630a_bank_b_update_status(struct backlight_device *bl)
 	if ((pwm_ctrl & LM3630A_PWM_BANK_B) != 0) {
 		lm3630a_pwm_ctrl(pchip, bl->props.brightness,
 				 bl->props.max_brightness);
-		return bl->props.brightness;
+		return 0;
 	}
 
 	/* disable sleep */

@@ -287,8 +287,8 @@ static int lm3630a_bank_b_update_status(struct backlight_device *bl)
 	return 0;
 
 out_i2c_err:
-	dev_err(pchip->dev, "i2c failed to access REG_CTRL\n");
-	return bl->props.brightness;
+	dev_err(pchip->dev, "i2c failed to access (%pe)\n", ERR_PTR(ret));
+	return ret;
 }
 
 static int lm3630a_bank_b_get_brightness(struct backlight_device *bl)

-- 
2.30.2

On Mon, Jun 21, 2021 at 02:21:47PM +0200, Uwe Kleine-König wrote:

According to <linux/backlight.h> .update_status() is supposed to
return 0 on success and a negative error code otherwise. Adapt
lm3630a_bank_a_update_status() and lm3630a_bank_b_update_status() to
actually do it.

While touching that also add the error code to the failure message.

Signed-off-by: Uwe Kleine-König <redacted>

Reviewed-by: Daniel Thompson <redacted>


Daniel.

On Mon, Jun 21, 2021 at 02:21:48PM +0200, Uwe Kleine-König wrote:

The practical upside here is that this only needs a single API call to
program the hardware which (depending on the underlaying hardware) can
be more effective and prevents glitches.

Up to now the return value of the pwm functions was ignored. Fix this
and propagate the error to the caller.

Signed-off-by: Uwe Kleine-König <redacted>

Reviewed-by: Daniel Thompson <redacted>


Daniel.

On Mon, 21 Jun 2021, Uwe Kleine-König wrote:

According to <linux/backlight.h> .update_status() is supposed to
return 0 on success and a negative error code otherwise. Adapt
lm3630a_bank_a_update_status() and lm3630a_bank_b_update_status() to
actually do it.

While touching that also add the error code to the failure message.

Signed-off-by: Uwe Kleine-König <redacted>
---
 drivers/video/backlight/lm3630a_bl.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Fixed the subject line for you and applied, thanks.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

On Mon, 21 Jun 2021, Uwe Kleine-König wrote:

The practical upside here is that this only needs a single API call to
program the hardware which (depending on the underlaying hardware) can
be more effective and prevents glitches.

Up to now the return value of the pwm functions was ignored. Fix this
and propagate the error to the caller.

Signed-off-by: Uwe Kleine-König <redacted>
---
 drivers/video/backlight/lm3630a_bl.c | 42 +++++++++++++---------------
 1 file changed, 19 insertions(+), 23 deletions(-)

Fixed the subject line and applied, thanks.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Hi Lee,

On Tue, Jun 22, 2021 at 02:12:57PM +0100, Lee Jones wrote:

On Mon, 21 Jun 2021, Uwe Kleine-König wrote:

quoted

The practical upside here is that this only needs a single API call to
program the hardware which (depending on the underlaying hardware) can
be more effective and prevents glitches.

Up to now the return value of the pwm functions was ignored. Fix this
and propagate the error to the caller.

Signed-off-by: Uwe Kleine-König <redacted>
---
 drivers/video/backlight/lm3630a_bl.c | 42 +++++++++++++---------------
 1 file changed, 19 insertions(+), 23 deletions(-)

Fixed the subject line and applied, thanks.

It's not obvious to me what needed fixing here, and I don't find where
you the patches, neither in next nor in
https://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight.git; so I
cannot check what you actually changed.

I assume you did s/lm3630a/lm3630a_bl/ ? I didn't because it felt
tautological.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

On Thu, 24 Jun 2021, Uwe Kleine-König wrote:

Hi Lee,

On Tue, Jun 22, 2021 at 02:12:57PM +0100, Lee Jones wrote:

quoted

On Mon, 21 Jun 2021, Uwe Kleine-König wrote:

quoted

The practical upside here is that this only needs a single API call to
program the hardware which (depending on the underlaying hardware) can
be more effective and prevents glitches.

Up to now the return value of the pwm functions was ignored. Fix this
and propagate the error to the caller.

Signed-off-by: Uwe Kleine-König <redacted>
---
 drivers/video/backlight/lm3630a_bl.c | 42 +++++++++++++---------------
 1 file changed, 19 insertions(+), 23 deletions(-)

Fixed the subject line and applied, thanks.

It's not obvious to me what needed fixing here, and I don't find where
you the patches, neither in next nor in
https://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight.git; so I
cannot check what you actually changed.

I assume you did s/lm3630a/lm3630a_bl/ ? I didn't because it felt
tautological.

No, but perhaps I should have.  Format goes:

<backlight>: <driver_file_name>: <Subject starting with uppercase>

Where <driver_file_name> has the file extension removed.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog