[PATCH v2] backlight: lp855x: Switch to atomic PWM API

[PATCH v2] backlight: lp855x: Switch to atomic PWM API

[Maíra Canal]

Remove legacy PWM interface (pwm_config, pwm_enable, pwm_disable) and
replace it for the atomic PWM API.

Signed-off-by: Maíra Canal <maira.canal@usp.br>
Reported-by: kernel test robot <lkp@intel.com>
---
V1 -> V2: Initializing variable and simplyfing conditional loop
---
 drivers/video/backlight/lp855x_bl.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index e94932c69f54..a895a8ca6d26 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -233,9 +233,8 @@ static int lp855x_configure(struct lp855x *lp)
 
 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 {
-	unsigned int period = lp->pdata->period_ns;
-	unsigned int duty = br * period / max_br;
-	struct pwm_device *pwm;
+	struct pwm_device *pwm = NULL;
+	struct pwm_state state;
 
 	/* request pwm device with the consumer name */
 	if (!lp->pwm) {
@@ -244,19 +243,15 @@ static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 			return;
 
 		lp->pwm = pwm;
-
-		/*
-		 * FIXME: pwm_apply_args() should be removed when switching to
-		 * the atomic PWM API.
-		 */
-		pwm_apply_args(pwm);
 	}
 
-	pwm_config(lp->pwm, duty, period);
-	if (duty)
-		pwm_enable(lp->pwm);
-	else
-		pwm_disable(lp->pwm);
+	pwm_init_state(pwm, &state);
+
+	state.period = lp->pdata->period_ns;
+	state.duty_cycle = br * state.period / max_br;
+	state.enabled = state.duty_cycle;
+
+	pwm_apply_state(pwm, &state);
 }
 
 static int lp855x_bl_update_status(struct backlight_device *bl)
-- 
2.31.1

Re: [PATCH v2] backlight: lp855x: Switch to atomic PWM API

[Uwe Kleine-König]

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On Wed, Oct 27, 2021 at 03:45:40PM -0300, Maíra Canal wrote:
> Remove legacy PWM interface (pwm_config, pwm_enable, pwm_disable) and
> replace it for the atomic PWM API.
> 
> Signed-off-by: Maíra Canal <maira.canal@usp.br>
> Reported-by: kernel test robot <lkp@intel.com>
> ---
> V1 -> V2: Initializing variable and simplyfing conditional loop
> ---
>  drivers/video/backlight/lp855x_bl.c | 23 +++++++++--------------
>  1 file changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
> index e94932c69f54..a895a8ca6d26 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -233,9 +233,8 @@ static int lp855x_configure(struct lp855x *lp)
>  
>  static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
>  {
> -	unsigned int period = lp->pdata->period_ns;
> -	unsigned int duty = br * period / max_br;
> -	struct pwm_device *pwm;
> +	struct pwm_device *pwm = NULL;
> +	struct pwm_state state;
>  
>  	/* request pwm device with the consumer name */
>  	if (!lp->pwm) {
> @@ -244,19 +243,15 @@ static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
>  			return;
>  
>  		lp->pwm = pwm;
> -
> -		/*
> -		 * FIXME: pwm_apply_args() should be removed when switching to
> -		 * the atomic PWM API.
> -		 */
> -		pwm_apply_args(pwm);
>  	}
>  
> -	pwm_config(lp->pwm, duty, period);
> -	if (duty)
> -		pwm_enable(lp->pwm);
> -	else
> -		pwm_disable(lp->pwm);
> +	pwm_init_state(pwm, &state);

This is broken. If lp->pwm is already set at function entry, pwm is
NULL.

Best regards
Uwe

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

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