[PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Lino Sanfilippo]

Use the newer .apply function of pwm_ops instead of .config, .enable,
.disable and .set_polarity. This guarantees atomic changes of the pwm
controller configuration. It also reduces the size of the driver.

Since now period is a 64 bit value, add an extra check to reject periods
that exceed the possible max value for the 32 bit register.

This has been tested on a Raspberry PI 4.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---

v3: Check against period truncation (based on a review by Uwe Kleine-König)
v2: Fix compiler error for 64 bit builds

 drivers/pwm/pwm-bcm2835.c | 72 +++++++++++++++++------------------------------
 1 file changed, 26 insertions(+), 46 deletions(-)

diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
index 6841dcf..d339898 100644
--- a/drivers/pwm/pwm-bcm2835.c
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -58,13 +58,15 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	writel(value, pc->base + PWM_CONTROL);
 }
 
-static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			      int duty_ns, int period_ns)
+static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			     const struct pwm_state *state)
 {
+
 	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 	unsigned long rate = clk_get_rate(pc->clk);
+	unsigned long long period;
 	unsigned long scaler;
-	u32 period;
+	u32 val;
 
 	if (!rate) {
 		dev_err(pc->dev, "failed to get clock rate\n");
@@ -72,65 +74,43 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 	scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
-	period = DIV_ROUND_CLOSEST(period_ns, scaler);
+	/* set period */
+	period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
 
-	if (period < PERIOD_MIN)
+	/* dont accept a period that is too small or has been truncated */
+	if ((period < PERIOD_MIN) || (period > U32_MAX))
 		return -EINVAL;
 
-	writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
-	       pc->base + DUTY(pwm->hwpwm));
-	writel(period, pc->base + PERIOD(pwm->hwpwm));
-
-	return 0;
-}
-
-static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	u32 value;
-
-	value = readl(pc->base + PWM_CONTROL);
-	value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
-	writel(value, pc->base + PWM_CONTROL);
-
-	return 0;
-}
-
-static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	u32 value;
+	writel((u32) period, pc->base + PERIOD(pwm->hwpwm));
 
-	value = readl(pc->base + PWM_CONTROL);
-	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
-	writel(value, pc->base + PWM_CONTROL);
-}
+	/* set duty cycle */
+	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
+	writel(val, pc->base + DUTY(pwm->hwpwm));
 
-static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
-				enum pwm_polarity polarity)
-{
-	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	u32 value;
+	/* set polarity */
+	val = readl(pc->base + PWM_CONTROL);
 
-	value = readl(pc->base + PWM_CONTROL);
+	if (state->polarity == PWM_POLARITY_NORMAL)
+		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
+	else
+		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
 
-	if (polarity == PWM_POLARITY_NORMAL)
-		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
+	/* enable/disable */
+	if (state->enabled)
+		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
 	else
-		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
+		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
 
-	writel(value, pc->base + PWM_CONTROL);
+	writel(val, pc->base + PWM_CONTROL);
 
 	return 0;
 }
 
+
 static const struct pwm_ops bcm2835_pwm_ops = {
 	.request = bcm2835_pwm_request,
 	.free = bcm2835_pwm_free,
-	.config = bcm2835_pwm_config,
-	.enable = bcm2835_pwm_enable,
-	.disable = bcm2835_pwm_disable,
-	.set_polarity = bcm2835_set_polarity,
+	.apply = bcm2835_pwm_apply,
 	.owner = THIS_MODULE,
 };
 
-- 
2.7.4

[PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Lino Sanfilippo]

Use the newer .apply function of pwm_ops instead of .config, .enable,
.disable and .set_polarity. This guarantees atomic changes of the pwm
controller configuration. It also reduces the size of the driver.

Since now period is a 64 bit value, add an extra check to reject periods
that exceed the possible max value for the 32 bit register.

This has been tested on a Raspberry PI 4.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---

v3: Check against period truncation (based on a review by Uwe Kleine-König)
v2: Fix compiler error for 64 bit builds

 drivers/pwm/pwm-bcm2835.c | 72 +++++++++++++++++------------------------------
 1 file changed, 26 insertions(+), 46 deletions(-)

diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
index 6841dcf..d339898 100644
--- a/drivers/pwm/pwm-bcm2835.c
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -58,13 +58,15 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	writel(value, pc->base + PWM_CONTROL);
 }
 
-static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			      int duty_ns, int period_ns)
+static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			     const struct pwm_state *state)
 {
+
 	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 	unsigned long rate = clk_get_rate(pc->clk);
+	unsigned long long period;
 	unsigned long scaler;
-	u32 period;
+	u32 val;
 
 	if (!rate) {
 		dev_err(pc->dev, "failed to get clock rate\n");
@@ -72,65 +74,43 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 	scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
-	period = DIV_ROUND_CLOSEST(period_ns, scaler);
+	/* set period */
+	period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
 
-	if (period < PERIOD_MIN)
+	/* dont accept a period that is too small or has been truncated */
+	if ((period < PERIOD_MIN) || (period > U32_MAX))
 		return -EINVAL;
 
-	writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
-	       pc->base + DUTY(pwm->hwpwm));
-	writel(period, pc->base + PERIOD(pwm->hwpwm));
-
-	return 0;
-}
-
-static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	u32 value;
-
-	value = readl(pc->base + PWM_CONTROL);
-	value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
-	writel(value, pc->base + PWM_CONTROL);
-
-	return 0;
-}
-
-static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	u32 value;
+	writel((u32) period, pc->base + PERIOD(pwm->hwpwm));
 
-	value = readl(pc->base + PWM_CONTROL);
-	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
-	writel(value, pc->base + PWM_CONTROL);
-}
+	/* set duty cycle */
+	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
+	writel(val, pc->base + DUTY(pwm->hwpwm));
 
-static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
-				enum pwm_polarity polarity)
-{
-	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	u32 value;
+	/* set polarity */
+	val = readl(pc->base + PWM_CONTROL);
 
-	value = readl(pc->base + PWM_CONTROL);
+	if (state->polarity == PWM_POLARITY_NORMAL)
+		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
+	else
+		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
 
-	if (polarity == PWM_POLARITY_NORMAL)
-		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
+	/* enable/disable */
+	if (state->enabled)
+		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
 	else
-		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
+		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
 
-	writel(value, pc->base + PWM_CONTROL);
+	writel(val, pc->base + PWM_CONTROL);
 
 	return 0;
 }
 
+
 static const struct pwm_ops bcm2835_pwm_ops = {
 	.request = bcm2835_pwm_request,
 	.free = bcm2835_pwm_free,
-	.config = bcm2835_pwm_config,
-	.enable = bcm2835_pwm_enable,
-	.disable = bcm2835_pwm_disable,
-	.set_polarity = bcm2835_set_polarity,
+	.apply = bcm2835_pwm_apply,
 	.owner = THIS_MODULE,
 };
 
-- 
2.7.4

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Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Uwe Kleine-König]

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Hello Lino,

On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> Use the newer .apply function of pwm_ops instead of .config, .enable,
> .disable and .set_polarity. This guarantees atomic changes of the pwm
> controller configuration. It also reduces the size of the driver.
> 
> Since now period is a 64 bit value, add an extra check to reject periods
> that exceed the possible max value for the 32 bit register.
> 
> This has been tested on a Raspberry PI 4.

This looks right, just two small nitpicks below.

> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
> ---
> 
> v3: Check against period truncation (based on a review by Uwe Kleine-König)
> v2: Fix compiler error for 64 bit builds
> 
>  drivers/pwm/pwm-bcm2835.c | 72 +++++++++++++++++------------------------------
>  1 file changed, 26 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
> index 6841dcf..d339898 100644
> --- a/drivers/pwm/pwm-bcm2835.c
> +++ b/drivers/pwm/pwm-bcm2835.c
> @@ -58,13 +58,15 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
>  	writel(value, pc->base + PWM_CONTROL);
>  }
>  
> -static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> -			      int duty_ns, int period_ns)
> +static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			     const struct pwm_state *state)
>  {
> +
>  	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
>  	unsigned long rate = clk_get_rate(pc->clk);
> +	unsigned long long period;
>  	unsigned long scaler;
> -	u32 period;
> +	u32 val;
>  
>  	if (!rate) {
>  		dev_err(pc->dev, "failed to get clock rate\n");
> @@ -72,65 +74,43 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  	}
>  
>  	scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
> -	period = DIV_ROUND_CLOSEST(period_ns, scaler);
> +	/* set period */
> +	period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
>  
> -	if (period < PERIOD_MIN)
> +	/* dont accept a period that is too small or has been truncated */
> +	if ((period < PERIOD_MIN) || (period > U32_MAX))
>  		return -EINVAL;
>  
> -	writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
> -	       pc->base + DUTY(pwm->hwpwm));
> -	writel(period, pc->base + PERIOD(pwm->hwpwm));
> -
> -	return 0;
> -}
> -
> -static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> -	u32 value;
> -
> -	value = readl(pc->base + PWM_CONTROL);
> -	value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> -	writel(value, pc->base + PWM_CONTROL);
> -
> -	return 0;
> -}
> -
> -static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> -	u32 value;
> +	writel((u32) period, pc->base + PERIOD(pwm->hwpwm));

This cast isn't necessary. (And if it was, I *think* the space between
"(u32)" and "period" is wrong. But my expectation that checkpatch warns
about this is wrong, so take this with a grain of salt.)

> -	value = readl(pc->base + PWM_CONTROL);
> -	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> -	writel(value, pc->base + PWM_CONTROL);
> -}
> +	/* set duty cycle */
> +	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
> +	writel(val, pc->base + DUTY(pwm->hwpwm));
>  
> -static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> -				enum pwm_polarity polarity)
> -{
> -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> -	u32 value;
> +	/* set polarity */
> +	val = readl(pc->base + PWM_CONTROL);
>  
> -	value = readl(pc->base + PWM_CONTROL);
> +	if (state->polarity == PWM_POLARITY_NORMAL)
> +		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> +	else
> +		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
>  
> -	if (polarity == PWM_POLARITY_NORMAL)
> -		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> +	/* enable/disable */
> +	if (state->enabled)
> +		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
>  	else
> -		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> +		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
>  
> -	writel(value, pc->base + PWM_CONTROL);
> +	writel(val, pc->base + PWM_CONTROL);
>  
>  	return 0;
>  }
>  
> +

I wouldn't have added this empty line. But I guess that's subjective. Or
did you add this by mistake?

>  static const struct pwm_ops bcm2835_pwm_ops = {
>  	.request = bcm2835_pwm_request,
>  	.free = bcm2835_pwm_free,
> -	.config = bcm2835_pwm_config,
> -	.enable = bcm2835_pwm_enable,
> -	.disable = bcm2835_pwm_disable,
> -	.set_polarity = bcm2835_set_polarity,
> +	.apply = bcm2835_pwm_apply,
>  	.owner = THIS_MODULE,
>  };

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

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Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Uwe Kleine-König]

[-- Attachment #1.1: Type: text/plain, Size: 5020 bytes --]

Hello Lino,

On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> Use the newer .apply function of pwm_ops instead of .config, .enable,
> .disable and .set_polarity. This guarantees atomic changes of the pwm
> controller configuration. It also reduces the size of the driver.
> 
> Since now period is a 64 bit value, add an extra check to reject periods
> that exceed the possible max value for the 32 bit register.
> 
> This has been tested on a Raspberry PI 4.

This looks right, just two small nitpicks below.

> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
> ---
> 
> v3: Check against period truncation (based on a review by Uwe Kleine-König)
> v2: Fix compiler error for 64 bit builds
> 
>  drivers/pwm/pwm-bcm2835.c | 72 +++++++++++++++++------------------------------
>  1 file changed, 26 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
> index 6841dcf..d339898 100644
> --- a/drivers/pwm/pwm-bcm2835.c
> +++ b/drivers/pwm/pwm-bcm2835.c
> @@ -58,13 +58,15 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
>  	writel(value, pc->base + PWM_CONTROL);
>  }
>  
> -static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> -			      int duty_ns, int period_ns)
> +static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			     const struct pwm_state *state)
>  {
> +
>  	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
>  	unsigned long rate = clk_get_rate(pc->clk);
> +	unsigned long long period;
>  	unsigned long scaler;
> -	u32 period;
> +	u32 val;
>  
>  	if (!rate) {
>  		dev_err(pc->dev, "failed to get clock rate\n");
> @@ -72,65 +74,43 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  	}
>  
>  	scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
> -	period = DIV_ROUND_CLOSEST(period_ns, scaler);
> +	/* set period */
> +	period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
>  
> -	if (period < PERIOD_MIN)
> +	/* dont accept a period that is too small or has been truncated */
> +	if ((period < PERIOD_MIN) || (period > U32_MAX))
>  		return -EINVAL;
>  
> -	writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
> -	       pc->base + DUTY(pwm->hwpwm));
> -	writel(period, pc->base + PERIOD(pwm->hwpwm));
> -
> -	return 0;
> -}
> -
> -static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> -	u32 value;
> -
> -	value = readl(pc->base + PWM_CONTROL);
> -	value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> -	writel(value, pc->base + PWM_CONTROL);
> -
> -	return 0;
> -}
> -
> -static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> -	u32 value;
> +	writel((u32) period, pc->base + PERIOD(pwm->hwpwm));

This cast isn't necessary. (And if it was, I *think* the space between
"(u32)" and "period" is wrong. But my expectation that checkpatch warns
about this is wrong, so take this with a grain of salt.)

> -	value = readl(pc->base + PWM_CONTROL);
> -	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> -	writel(value, pc->base + PWM_CONTROL);
> -}
> +	/* set duty cycle */
> +	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
> +	writel(val, pc->base + DUTY(pwm->hwpwm));
>  
> -static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> -				enum pwm_polarity polarity)
> -{
> -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> -	u32 value;
> +	/* set polarity */
> +	val = readl(pc->base + PWM_CONTROL);
>  
> -	value = readl(pc->base + PWM_CONTROL);
> +	if (state->polarity == PWM_POLARITY_NORMAL)
> +		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> +	else
> +		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
>  
> -	if (polarity == PWM_POLARITY_NORMAL)
> -		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> +	/* enable/disable */
> +	if (state->enabled)
> +		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
>  	else
> -		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> +		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
>  
> -	writel(value, pc->base + PWM_CONTROL);
> +	writel(val, pc->base + PWM_CONTROL);
>  
>  	return 0;
>  }
>  
> +

I wouldn't have added this empty line. But I guess that's subjective. Or
did you add this by mistake?

>  static const struct pwm_ops bcm2835_pwm_ops = {
>  	.request = bcm2835_pwm_request,
>  	.free = bcm2835_pwm_free,
> -	.config = bcm2835_pwm_config,
> -	.enable = bcm2835_pwm_enable,
> -	.disable = bcm2835_pwm_disable,
> -	.set_polarity = bcm2835_set_polarity,
> +	.apply = bcm2835_pwm_apply,
>  	.owner = THIS_MODULE,
>  };

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

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Aw: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Lino Sanfilippo]

Hi Uwe

> Hello Lino,
>
> On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> > Use the newer .apply function of pwm_ops instead of .config, .enable,
> > .disable and .set_polarity. This guarantees atomic changes of the pwm
> > controller configuration. It also reduces the size of the driver.
> >
> > Since now period is a 64 bit value, add an extra check to reject periods
> > that exceed the possible max value for the 32 bit register.
> >
> > This has been tested on a Raspberry PI 4.
>
> This looks right, just two small nitpicks below.
>

>
> This cast isn't necessary. (And if it was, I *think* the space between
> "(u32)" and "period" is wrong. But my expectation that checkpatch warns
> about this is wrong, so take this with a grain of salt.)

OK, I will omit the cast in the next patch version (it was primarily
meant for documentation purposes but now it seems to me rather
unusual for kernel code)

>
> > -	value = readl(pc->base + PWM_CONTROL);
> > -	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > -	writel(value, pc->base + PWM_CONTROL);
> > -}
> > +	/* set duty cycle */
> > +	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
> > +	writel(val, pc->base + DUTY(pwm->hwpwm));
> >
> > -static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> > -				enum pwm_polarity polarity)
> > -{
> > -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> > -	u32 value;
> > +	/* set polarity */
> > +	val = readl(pc->base + PWM_CONTROL);
> >
> > -	value = readl(pc->base + PWM_CONTROL);
> > +	if (state->polarity == PWM_POLARITY_NORMAL)
> > +		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > +	else
> > +		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> >
> > -	if (polarity == PWM_POLARITY_NORMAL)
> > -		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > +	/* enable/disable */
> > +	if (state->enabled)
> > +		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> >  	else
> > -		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> > +		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> >
> > -	writel(value, pc->base + PWM_CONTROL);
> > +	writel(val, pc->base + PWM_CONTROL);
> >
> >  	return 0;
> >  }
> >
> > +
>
> I wouldn't have added this empty line. But I guess that's subjective. Or
> did you add this by mistake?

I cannot remember that the line was added by intention, so I am fine to remove it.

Thanks and regards,
Lino

Aw: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Lino Sanfilippo]

Hi Uwe

> Hello Lino,
>
> On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> > Use the newer .apply function of pwm_ops instead of .config, .enable,
> > .disable and .set_polarity. This guarantees atomic changes of the pwm
> > controller configuration. It also reduces the size of the driver.
> >
> > Since now period is a 64 bit value, add an extra check to reject periods
> > that exceed the possible max value for the 32 bit register.
> >
> > This has been tested on a Raspberry PI 4.
>
> This looks right, just two small nitpicks below.
>

>
> This cast isn't necessary. (And if it was, I *think* the space between
> "(u32)" and "period" is wrong. But my expectation that checkpatch warns
> about this is wrong, so take this with a grain of salt.)

OK, I will omit the cast in the next patch version (it was primarily
meant for documentation purposes but now it seems to me rather
unusual for kernel code)

>
> > -	value = readl(pc->base + PWM_CONTROL);
> > -	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > -	writel(value, pc->base + PWM_CONTROL);
> > -}
> > +	/* set duty cycle */
> > +	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
> > +	writel(val, pc->base + DUTY(pwm->hwpwm));
> >
> > -static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> > -				enum pwm_polarity polarity)
> > -{
> > -	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> > -	u32 value;
> > +	/* set polarity */
> > +	val = readl(pc->base + PWM_CONTROL);
> >
> > -	value = readl(pc->base + PWM_CONTROL);
> > +	if (state->polarity == PWM_POLARITY_NORMAL)
> > +		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > +	else
> > +		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> >
> > -	if (polarity == PWM_POLARITY_NORMAL)
> > -		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > +	/* enable/disable */
> > +	if (state->enabled)
> > +		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> >  	else
> > -		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> > +		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> >
> > -	writel(value, pc->base + PWM_CONTROL);
> > +	writel(val, pc->base + PWM_CONTROL);
> >
> >  	return 0;
> >  }
> >
> > +
>
> I wouldn't have added this empty line. But I guess that's subjective. Or
> did you add this by mistake?

I cannot remember that the line was added by intention, so I am fine to remove it.

Thanks and regards,
Lino

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Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Uwe Kleine-König]

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Hello,

On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> Use the newer .apply function of pwm_ops instead of .config, .enable,
> .disable and .set_polarity. This guarantees atomic changes of the pwm
> controller configuration. It also reduces the size of the driver.
> 
> Since now period is a 64 bit value, add an extra check to reject periods
> that exceed the possible max value for the 32 bit register.
> 
> This has been tested on a Raspberry PI 4.
> 
> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Side note: I'm a bit surprised about the output of

	b4 diff 1607464905-16630-1-git-send-email-LinoSanfilippo@gmx.de

This is probably due to the fact that compared to v3 you also rebased.
Still the diff is quite big.

Best regards and thanks for your patch
Uwe

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

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Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Uwe Kleine-König]

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Hello,

On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> Use the newer .apply function of pwm_ops instead of .config, .enable,
> .disable and .set_polarity. This guarantees atomic changes of the pwm
> controller configuration. It also reduces the size of the driver.
> 
> Since now period is a 64 bit value, add an extra check to reject periods
> that exceed the possible max value for the 32 bit register.
> 
> This has been tested on a Raspberry PI 4.
> 
> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Side note: I'm a bit surprised about the output of

	b4 diff 1607464905-16630-1-git-send-email-LinoSanfilippo@gmx.de

This is probably due to the fact that compared to v3 you also rebased.
Still the diff is quite big.

Best regards and thanks for your patch
Uwe

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

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Aw: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Lino Sanfilippo]

Hi Uwe,

> Gesendet: Donnerstag, 10. Dezember 2020 um 12:43 Uhr
> Von: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
> An: "Lino Sanfilippo" <LinoSanfilippo@gmx.de>
> Cc: thierry.reding@gmail.com, lee.jones@linaro.org, nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com, sean@mess.org, sbranden@broadcom.com, bcm-kernel-feedback-list@broadcom.com, linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
> Betreff: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

> 
> Side note: I'm a bit surprised about the output of
> 
> 	b4 diff 1607464905-16630-1-git-send-email-LinoSanfilippo@gmx.de
> 
> This is probably due to the fact that compared to v3 you also rebased.
> Still the diff is quite big.

You are right, I made a rebase before I created the last patch, sorry for the confusion this caused.
Anyway, thanks for the review(s)!

Regards,
Lino

Aw: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Lino Sanfilippo]

Hi Uwe,

> Gesendet: Donnerstag, 10. Dezember 2020 um 12:43 Uhr
> Von: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
> An: "Lino Sanfilippo" <LinoSanfilippo@gmx.de>
> Cc: thierry.reding@gmail.com, lee.jones@linaro.org, nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com, sean@mess.org, sbranden@broadcom.com, bcm-kernel-feedback-list@broadcom.com, linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
> Betreff: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

> 
> Side note: I'm a bit surprised about the output of
> 
> 	b4 diff 1607464905-16630-1-git-send-email-LinoSanfilippo@gmx.de
> 
> This is probably due to the fact that compared to v3 you also rebased.
> Still the diff is quite big.

You are right, I made a rebase before I created the last patch, sorry for the confusion this caused.
Anyway, thanks for the review(s)!

Regards,
Lino



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Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Uwe Kleine-König]

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On Fri, Dec 11, 2020 at 10:28:35AM +0100, Lino Sanfilippo wrote:
> Hi Uwe,
> 
> > Gesendet: Donnerstag, 10. Dezember 2020 um 12:43 Uhr
> > Von: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
> > An: "Lino Sanfilippo" <LinoSanfilippo@gmx.de>
> > Cc: thierry.reding@gmail.com, lee.jones@linaro.org, nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com, sean@mess.org, sbranden@broadcom.com, bcm-kernel-feedback-list@broadcom.com, linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
> > Betreff: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
> 
> > 
> > Side note: I'm a bit surprised about the output of
> > 
> > 	b4 diff 1607464905-16630-1-git-send-email-LinoSanfilippo@gmx.de
> > 
> > This is probably due to the fact that compared to v3 you also rebased.
> > Still the diff is quite big.
> 
> You are right, I made a rebase before I created the last patch, sorry for the confusion this caused.
> Anyway, thanks for the review(s)!

You did everything good enough. (To further improve, you could use
git-format-patch's --base option and mention a rebase in the series'
changelog; note this is quite high level critic.)

This was more me wondering the output is not easier to use. (And note I
also showed the wrong commandline, but that doesn't resolve the issue.
The right command is:

	b4 diff 1607546905-20549-1-git-send-email-LinoSanfilippo@gmx.de

.)

Best regards
Uwe

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

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Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration

[Uwe Kleine-König]

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On Fri, Dec 11, 2020 at 10:28:35AM +0100, Lino Sanfilippo wrote:
> Hi Uwe,
> 
> > Gesendet: Donnerstag, 10. Dezember 2020 um 12:43 Uhr
> > Von: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
> > An: "Lino Sanfilippo" <LinoSanfilippo@gmx.de>
> > Cc: thierry.reding@gmail.com, lee.jones@linaro.org, nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com, sean@mess.org, sbranden@broadcom.com, bcm-kernel-feedback-list@broadcom.com, linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
> > Betreff: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
> 
> > 
> > Side note: I'm a bit surprised about the output of
> > 
> > 	b4 diff 1607464905-16630-1-git-send-email-LinoSanfilippo@gmx.de
> > 
> > This is probably due to the fact that compared to v3 you also rebased.
> > Still the diff is quite big.
> 
> You are right, I made a rebase before I created the last patch, sorry for the confusion this caused.
> Anyway, thanks for the review(s)!

You did everything good enough. (To further improve, you could use
git-format-patch's --base option and mention a rebase in the series'
changelog; note this is quite high level critic.)

This was more me wondering the output is not easier to use. (And note I
also showed the wrong commandline, but that doesn't resolve the issue.
The right command is:

	b4 diff 1607546905-20549-1-git-send-email-LinoSanfilippo@gmx.de

.)

Best regards
Uwe

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

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