[PATCH v2 1/2] backlight: lm3630a: fix return code of .update_status() callback

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() 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 | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index e88a2b0e5904..16a2658a72e1 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)

base-commit: 6efb943b8616ec53a5e444193dccf1af9ad627b5
-- 
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 | 34 +++++++++++++---------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index 16a2658a72e1..99eb8277149b 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);

@@ -563,11 +565,7 @@ 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

On Sun, Jun 20, 2021 at 09:39:27PM +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() to actually do it.

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

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

Thanks for this!

Reviewed-by: Daniel Thompson <redacted>


Daniel.

On Sun, Jun 20, 2021 at 09:39:28PM +0200, Uwe Kleine-König wrote:

My apologies for overlooking this at v1 (and even when reviewing the first of
the v2 patchs) but...  this fixes the code for bank A. Bank B also requires exactly
the same set of fixes!


Daniel.

On Mon, Jun 21, 2021 at 11:23:51AM +0100, Daniel Thompson wrote:

On Sun, Jun 20, 2021 at 09:39:27PM +0200, Uwe Kleine-König wrote:

quoted

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() to actually do it.

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

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

Thanks for this!

Reviewed-by: Daniel Thompson <redacted>

Sorry... looks like I was a little hasty here.

As mentioned in https://marc.info/?l=linux-fbdev&m=162427245024751&w=2
when lm3630a_bank_b_update_status() needs similar fixes.

Just wanted to put something in the ML record so Lee doesn't pick this
patch based on my R-b above...


Danieo.

Daniel.

quoted

---
 drivers/video/backlight/lm3630a_bl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index e88a2b0e5904..16a2658a72e1 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)

base-commit: 6efb943b8616ec53a5e444193dccf1af9ad627b5
-- 
2.30.2