[PATCH v2 0/6] pwm: mxs: add support for setting polarity via DT

[PATCH v2 0/6] pwm: mxs: add support for setting polarity via DT

[Rasmus Villemoes]

This series adds support for setting the polarity via DT to the
pwm-mxs driver.

The DT binding is updated, but I'm not touching the existing .dts or
.dtsi files - it seems that the same was done for bcm2835 in commits
46421d9d8e802e570dfa4d793a4938d2642ec7a7 and
8a88b2a2017d1e7e80db53080baff591fd454722, while
arch/arm/boot/dts/bcm283x.dtsi still has #pwm-cells = <2>.

v2:
- Rebase to v5.4-rc1
- Address comments from Uwe.
- Add Rob's ack to patch 4.
- New patches 5 and 6. The last one is independent of the others, but
  I stumbled on this when rebasing and found the signature had
  changed.

Rasmus Villemoes (6):
  pwm: mxs: implement ->apply
  pwm: mxs: remove legacy methods
  pwm: mxs: add support for inverse polarity
  dt-bindings: pwm: mxs-pwm: Increase #pwm-cells
  pwm: mxs: avoid a division in mxs_pwm_apply()
  pwm: update comment on struct pwm_ops::apply

 .../devicetree/bindings/pwm/mxs-pwm.txt       |   4 +-
 drivers/pwm/pwm-mxs.c                         | 101 +++++++++---------
 include/linux/pwm.h                           |   5 +-
 3 files changed, 53 insertions(+), 57 deletions(-)

-- 
2.20.1

[PATCH v2 1/6] pwm: mxs: implement ->apply

[Rasmus Villemoes]

In preparation for supporting setting the polarity, switch the driver
to support the ->apply method.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/pwm/pwm-mxs.c | 70 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
index b14376b47ac8..10efd3de0bb3 100644
--- a/drivers/pwm/pwm-mxs.c
+++ b/drivers/pwm/pwm-mxs.c
@@ -26,6 +26,7 @@
 #define  PERIOD_PERIOD_MAX	0x10000
 #define  PERIOD_ACTIVE_HIGH	(3 << 16)
 #define  PERIOD_INACTIVE_LOW	(2 << 18)
+#define  PERIOD_POLARITY_NORMAL	(PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
 #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
 #define  PERIOD_CDIV_MAX	8
 
@@ -41,6 +42,74 @@ struct mxs_pwm_chip {
 
 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
 
+static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			 const struct pwm_state *state)
+{
+	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
+	int ret, div = 0;
+	unsigned int period_cycles, duty_cycles;
+	unsigned long rate;
+	unsigned long long c;
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -ENOTSUPP;
+
+	/*
+	 * If the PWM channel is disabled, make sure to turn on the
+	 * clock before calling clk_get_rate() and writing to the
+	 * registers. Otherwise, just keep it enabled.
+	 */
+	if (!pwm_is_enabled(pwm)) {
+		ret = clk_prepare_enable(mxs->clk);
+		if (ret)
+			return ret;
+	}
+
+	if (!state->enabled && pwm_is_enabled(pwm))
+		writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
+
+	rate = clk_get_rate(mxs->clk);
+	while (1) {
+		c = rate / cdiv[div];
+		c = c * state->period;
+		do_div(c, 1000000000);
+		if (c < PERIOD_PERIOD_MAX)
+			break;
+		div++;
+		if (div >= PERIOD_CDIV_MAX)
+			return -EINVAL;
+	}
+
+	period_cycles = c;
+	c *= state->duty_cycle;
+	do_div(c, state->period);
+	duty_cycles = c;
+
+	/*
+	 * The data sheet the says registers must be written to in
+	 * this order (ACTIVEn, then PERIODn). Also, the new settings
+	 * only take effect at the beginning of a new period, avoiding
+	 * glitches.
+	 */
+	writel(duty_cycles << 16,
+	       mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
+	writel(PERIOD_PERIOD(period_cycles) | PERIOD_POLARITY_NORMAL | PERIOD_CDIV(div),
+	       mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
+
+	if (state->enabled) {
+		if (!pwm_is_enabled(pwm)) {
+			/*
+			 * The clock was enabled above. Just enable
+			 * the channel in the control register.
+			 */
+			writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
+		}
+	} else {
+		clk_disable_unprepare(mxs->clk);
+	}
+	return 0;
+}
+
 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			  int duty_ns, int period_ns)
 {
@@ -116,6 +185,7 @@ static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 }
 
 static const struct pwm_ops mxs_pwm_ops = {
+	.apply = mxs_pwm_apply,
 	.config = mxs_pwm_config,
 	.enable = mxs_pwm_enable,
 	.disable = mxs_pwm_disable,
-- 
2.20.1

Re: [PATCH v2 1/6] pwm: mxs: implement ->apply

[Uwe Kleine-König]

Hello,

On Fri, Oct 04, 2019 at 03:32:02PM +0200, Rasmus Villemoes wrote:
> In preparation for supporting setting the polarity, switch the driver
> to support the ->apply method.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  drivers/pwm/pwm-mxs.c | 70 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
> index b14376b47ac8..10efd3de0bb3 100644
> --- a/drivers/pwm/pwm-mxs.c
> +++ b/drivers/pwm/pwm-mxs.c
> @@ -26,6 +26,7 @@
>  #define  PERIOD_PERIOD_MAX	0x10000
>  #define  PERIOD_ACTIVE_HIGH	(3 << 16)
>  #define  PERIOD_INACTIVE_LOW	(2 << 18)
> +#define  PERIOD_POLARITY_NORMAL	(PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
>  #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
>  #define  PERIOD_CDIV_MAX	8
>  
> @@ -41,6 +42,74 @@ struct mxs_pwm_chip {
>  
>  #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
>  
> +static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			 const struct pwm_state *state)
> +{
> +	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
> +	int ret, div = 0;
> +	unsigned int period_cycles, duty_cycles;
> +	unsigned long rate;
> +	unsigned long long c;
> +
> +	if (state->polarity != PWM_POLARITY_NORMAL)
> +		return -ENOTSUPP;
> +
> +	/*
> +	 * If the PWM channel is disabled, make sure to turn on the
> +	 * clock before calling clk_get_rate() and writing to the
> +	 * registers. Otherwise, just keep it enabled.
> +	 */
> +	if (!pwm_is_enabled(pwm)) {
> +		ret = clk_prepare_enable(mxs->clk);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (!state->enabled && pwm_is_enabled(pwm))
> +		writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);

@Thierry: I wonder if it would be beneficial to stop the calculation of
register contents if !state->enabled here. The only drawback (I'm aware)
is that pwm_get_state won't return the previously set .period and
.duty_cycle. (I also wonder if we should return (e.g.) .duty = 0,
.period = 1 in pwm_get_state() if the PWM is off.)

For the patch (which is orthogonal regarding the above question):

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

Best regards
Uwe

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

[PATCH v2 2/6] pwm: mxs: remove legacy methods

[Rasmus Villemoes]

Since we now have ->apply, these are no longer relevant.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/pwm/pwm-mxs.c | 77 -------------------------------------------
 1 file changed, 77 deletions(-)

diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
index 10efd3de0bb3..5a6835e18fc6 100644
--- a/drivers/pwm/pwm-mxs.c
+++ b/drivers/pwm/pwm-mxs.c
@@ -110,85 +110,8 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			  int duty_ns, int period_ns)
-{
-	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
-	int ret, div = 0;
-	unsigned int period_cycles, duty_cycles;
-	unsigned long rate;
-	unsigned long long c;
-
-	rate = clk_get_rate(mxs->clk);
-	while (1) {
-		c = rate / cdiv[div];
-		c = c * period_ns;
-		do_div(c, 1000000000);
-		if (c < PERIOD_PERIOD_MAX)
-			break;
-		div++;
-		if (div >= PERIOD_CDIV_MAX)
-			return -EINVAL;
-	}
-
-	period_cycles = c;
-	c *= duty_ns;
-	do_div(c, period_ns);
-	duty_cycles = c;
-
-	/*
-	 * If the PWM channel is disabled, make sure to turn on the clock
-	 * before writing the register. Otherwise, keep it enabled.
-	 */
-	if (!pwm_is_enabled(pwm)) {
-		ret = clk_prepare_enable(mxs->clk);
-		if (ret)
-			return ret;
-	}
-
-	writel(duty_cycles << 16,
-			mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
-	writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
-	       PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
-			mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
-
-	/*
-	 * If the PWM is not enabled, turn the clock off again to save power.
-	 */
-	if (!pwm_is_enabled(pwm))
-		clk_disable_unprepare(mxs->clk);
-
-	return 0;
-}
-
-static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
-	int ret;
-
-	ret = clk_prepare_enable(mxs->clk);
-	if (ret)
-		return ret;
-
-	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
-
-	return 0;
-}
-
-static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
-
-	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
-
-	clk_disable_unprepare(mxs->clk);
-}
-
 static const struct pwm_ops mxs_pwm_ops = {
 	.apply = mxs_pwm_apply,
-	.config = mxs_pwm_config,
-	.enable = mxs_pwm_enable,
-	.disable = mxs_pwm_disable,
 	.owner = THIS_MODULE,
 };
 
-- 
2.20.1

Re: [PATCH v2 2/6] pwm: mxs: remove legacy methods

[Uwe Kleine-König]

On Fri, Oct 04, 2019 at 03:32:03PM +0200, Rasmus Villemoes wrote:
> Since we now have ->apply, these are no longer relevant.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

nice and easy,

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

Best regards
Uwe

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

[PATCH v2 3/6] pwm: mxs: add support for inverse polarity

[Rasmus Villemoes]

If I'm reading of_pwm_xlate_with_flags() right, existing device trees
that set #pwm-cells = 2 will continue to work.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/pwm/pwm-mxs.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
index 5a6835e18fc6..57562221c439 100644
--- a/drivers/pwm/pwm-mxs.c
+++ b/drivers/pwm/pwm-mxs.c
@@ -25,8 +25,11 @@
 #define  PERIOD_PERIOD(p)	((p) & 0xffff)
 #define  PERIOD_PERIOD_MAX	0x10000
 #define  PERIOD_ACTIVE_HIGH	(3 << 16)
+#define  PERIOD_ACTIVE_LOW	(2 << 16)
+#define  PERIOD_INACTIVE_HIGH	(3 << 18)
 #define  PERIOD_INACTIVE_LOW	(2 << 18)
 #define  PERIOD_POLARITY_NORMAL	(PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
+#define  PERIOD_POLARITY_INVERSE	(PERIOD_ACTIVE_LOW | PERIOD_INACTIVE_HIGH)
 #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
 #define  PERIOD_CDIV_MAX	8
 
@@ -50,9 +53,7 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	unsigned int period_cycles, duty_cycles;
 	unsigned long rate;
 	unsigned long long c;
-
-	if (state->polarity != PWM_POLARITY_NORMAL)
-		return -ENOTSUPP;
+	unsigned int pol_bits;
 
 	/*
 	 * If the PWM channel is disabled, make sure to turn on the
@@ -91,9 +92,12 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * only take effect at the beginning of a new period, avoiding
 	 * glitches.
 	 */
+
+	pol_bits = state->polarity == PWM_POLARITY_NORMAL ?
+		PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE;
 	writel(duty_cycles << 16,
 	       mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
-	writel(PERIOD_PERIOD(period_cycles) | PERIOD_POLARITY_NORMAL | PERIOD_CDIV(div),
+	writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div),
 	       mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
 
 	if (state->enabled) {
@@ -135,6 +139,8 @@ static int mxs_pwm_probe(struct platform_device *pdev)
 
 	mxs->chip.dev = &pdev->dev;
 	mxs->chip.ops = &mxs_pwm_ops;
+	mxs->chip.of_xlate = of_pwm_xlate_with_flags;
+	mxs->chip.of_pwm_n_cells = 3;
 	mxs->chip.base = -1;
 
 	ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
-- 
2.20.1

Re: [PATCH v2 3/6] pwm: mxs: add support for inverse polarity

[Uwe Kleine-König]

On Fri, Oct 04, 2019 at 03:32:04PM +0200, Rasmus Villemoes wrote:
> If I'm reading of_pwm_xlate_with_flags() right, existing device trees
> that set #pwm-cells = 2 will continue to work.

Yes, that's what I expect, too.

> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  drivers/pwm/pwm-mxs.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
> index 5a6835e18fc6..57562221c439 100644
> --- a/drivers/pwm/pwm-mxs.c
> +++ b/drivers/pwm/pwm-mxs.c
> @@ -25,8 +25,11 @@
>  #define  PERIOD_PERIOD(p)	((p) & 0xffff)
>  #define  PERIOD_PERIOD_MAX	0x10000
>  #define  PERIOD_ACTIVE_HIGH	(3 << 16)
> +#define  PERIOD_ACTIVE_LOW	(2 << 16)
> +#define  PERIOD_INACTIVE_HIGH	(3 << 18)
>  #define  PERIOD_INACTIVE_LOW	(2 << 18)
>  #define  PERIOD_POLARITY_NORMAL	(PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
> +#define  PERIOD_POLARITY_INVERSE	(PERIOD_ACTIVE_LOW | PERIOD_INACTIVE_HIGH)
>  #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
>  #define  PERIOD_CDIV_MAX	8
>  
> @@ -50,9 +53,7 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  	unsigned int period_cycles, duty_cycles;
>  	unsigned long rate;
>  	unsigned long long c;
> -
> -	if (state->polarity != PWM_POLARITY_NORMAL)
> -		return -ENOTSUPP;
> +	unsigned int pol_bits;
>  
>  	/*
>  	 * If the PWM channel is disabled, make sure to turn on the
> @@ -91,9 +92,12 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  	 * only take effect at the beginning of a new period, avoiding
>  	 * glitches.
>  	 */
> +
> +	pol_bits = state->polarity == PWM_POLARITY_NORMAL ?
> +		PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE;
>  	writel(duty_cycles << 16,
>  	       mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
> -	writel(PERIOD_PERIOD(period_cycles) | PERIOD_POLARITY_NORMAL | PERIOD_CDIV(div),
> +	writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div),
>  	       mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);

Is the avoidance of glitches still true when period changes? I assume
that yes, but I wonder if you tested that.

Best regards
Uwe

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

[PATCH v2 4/6] dt-bindings: pwm: mxs-pwm: Increase #pwm-cells

[Rasmus Villemoes]

We need to increase the pwm-cells for the optional flags parameter, in
order to implement support for polarity setting via DT.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 Documentation/devicetree/bindings/pwm/mxs-pwm.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/mxs-pwm.txt b/Documentation/devicetree/bindings/pwm/mxs-pwm.txt
index 96cdde5f6208..1697dcd3b07c 100644
--- a/Documentation/devicetree/bindings/pwm/mxs-pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/mxs-pwm.txt
@@ -3,7 +3,7 @@ Freescale MXS PWM controller
 Required properties:
 - compatible: should be "fsl,imx23-pwm"
 - reg: physical base address and length of the controller's registers
-- #pwm-cells: should be 2. See pwm.txt in this directory for a description of
+- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
   the cells format.
 - fsl,pwm-number: the number of PWM devices
 
@@ -12,6 +12,6 @@ Example:
 pwm: pwm@80064000 {
 	compatible = "fsl,imx28-pwm", "fsl,imx23-pwm";
 	reg = <0x80064000 0x2000>;
-	#pwm-cells = <2>;
+	#pwm-cells = <3>;
 	fsl,pwm-number = <8>;
 };
-- 
2.20.1

Re: [PATCH v2 4/6] dt-bindings: pwm: mxs-pwm: Increase #pwm-cells

[Uwe Kleine-König]

On Fri, Oct 04, 2019 at 03:32:05PM +0200, Rasmus Villemoes wrote:
> We need to increase the pwm-cells for the optional flags parameter, in
> order to implement support for polarity setting via DT.
> 
> Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks
Uwe

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

[PATCH v2 5/6] pwm: mxs: avoid a division in mxs_pwm_apply()

[Rasmus Villemoes]

Since the divisor is not a compile-time constant (unless gcc somehow
decided to unroll the loop PERIOD_CDIV_MAX times), this does a
somewhat expensive 32/32 division. Replace that with a right shift.

We still have a 64/32 division just below, but at least in that
case the divisor is compile-time constant.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/pwm/pwm-mxs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
index 57562221c439..f2e57fcf8f8b 100644
--- a/drivers/pwm/pwm-mxs.c
+++ b/drivers/pwm/pwm-mxs.c
@@ -33,8 +33,8 @@
 #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
 #define  PERIOD_CDIV_MAX	8
 
-static const unsigned int cdiv[PERIOD_CDIV_MAX] = {
-	1, 2, 4, 8, 16, 64, 256, 1024
+static const u8 cdiv_shift[PERIOD_CDIV_MAX] = {
+	0, 1, 2, 3, 4, 6, 8, 10
 };
 
 struct mxs_pwm_chip {
@@ -71,7 +71,7 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	rate = clk_get_rate(mxs->clk);
 	while (1) {
-		c = rate / cdiv[div];
+		c = rate >> cdiv_shift[div];
 		c = c * state->period;
 		do_div(c, 1000000000);
 		if (c < PERIOD_PERIOD_MAX)
-- 
2.20.1

Re: [PATCH v2 5/6] pwm: mxs: avoid a division in mxs_pwm_apply()

[Uwe Kleine-König]

On Fri, Oct 04, 2019 at 03:32:06PM +0200, Rasmus Villemoes wrote:
> Since the divisor is not a compile-time constant (unless gcc somehow
> decided to unroll the loop PERIOD_CDIV_MAX times), this does a
> somewhat expensive 32/32 division. Replace that with a right shift.
> 
> We still have a 64/32 division just below, but at least in that
> case the divisor is compile-time constant.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

> ---
>  drivers/pwm/pwm-mxs.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
> index 57562221c439..f2e57fcf8f8b 100644
> --- a/drivers/pwm/pwm-mxs.c
> +++ b/drivers/pwm/pwm-mxs.c
> @@ -33,8 +33,8 @@
>  #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
>  #define  PERIOD_CDIV_MAX	8
>  
> -static const unsigned int cdiv[PERIOD_CDIV_MAX] = {
> -	1, 2, 4, 8, 16, 64, 256, 1024
> +static const u8 cdiv_shift[PERIOD_CDIV_MAX] = {
> +	0, 1, 2, 3, 4, 6, 8, 10

One small nitpick: I would like to see this name have a mxs_pwm_ prefix.
But even without this change:

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

Thanks
Uwe

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

[PATCH v2 6/6] pwm: update comment on struct pwm_ops::apply

[Rasmus Villemoes]

Commit 71523d1812ac (pwm: Ensure pwm_apply_state() doesn't modify the
state argument) updated the kernel-doc for pwm_apply_state(), but not
for the ->apply callback in the pwm_ops struct.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 include/linux/pwm.h | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index b2c9c460947d..0ef808d925bb 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -243,10 +243,7 @@ pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
  * @request: optional hook for requesting a PWM
  * @free: optional hook for freeing a PWM
  * @capture: capture and report PWM signal
- * @apply: atomically apply a new PWM config. The state argument
- *	   should be adjusted with the real hardware config (if the
- *	   approximate the period or duty_cycle value, state should
- *	   reflect it)
+ * @apply: atomically apply a new PWM config
  * @get_state: get the current PWM state. This function is only
  *	       called once per PWM device when the PWM chip is
  *	       registered.
-- 
2.20.1

Re: [PATCH v2 6/6] pwm: update comment on struct pwm_ops::apply

[Uwe Kleine-König]

On Fri, Oct 04, 2019 at 03:32:07PM +0200, Rasmus Villemoes wrote:
> Commit 71523d1812ac (pwm: Ensure pwm_apply_state() doesn't modify the
> state argument) updated the kernel-doc for pwm_apply_state(), but not
> for the ->apply callback in the pwm_ops struct.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  include/linux/pwm.h | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> index b2c9c460947d..0ef808d925bb 100644
> --- a/include/linux/pwm.h
> +++ b/include/linux/pwm.h
> @@ -243,10 +243,7 @@ pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
>   * @request: optional hook for requesting a PWM
>   * @free: optional hook for freeing a PWM
>   * @capture: capture and report PWM signal
> - * @apply: atomically apply a new PWM config. The state argument
> - *	   should be adjusted with the real hardware config (if the
> - *	   approximate the period or duty_cycle value, state should
> - *	   reflect it)
> + * @apply: atomically apply a new PWM config

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

Thanks
Uwe

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

Re: [PATCH v2 6/6] pwm: update comment on struct pwm_ops::apply

[Bjorn Andersson]

On Fri, Oct 4, 2019 at 6:33 AM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> Commit 71523d1812ac (pwm: Ensure pwm_apply_state() doesn't modify the
> state argument) updated the kernel-doc for pwm_apply_state(), but not
> for the ->apply callback in the pwm_ops struct.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

> ---
>  include/linux/pwm.h | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> index b2c9c460947d..0ef808d925bb 100644
> --- a/include/linux/pwm.h
> +++ b/include/linux/pwm.h
> @@ -243,10 +243,7 @@ pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
>   * @request: optional hook for requesting a PWM
>   * @free: optional hook for freeing a PWM
>   * @capture: capture and report PWM signal
> - * @apply: atomically apply a new PWM config. The state argument
> - *        should be adjusted with the real hardware config (if the
> - *        approximate the period or duty_cycle value, state should
> - *        reflect it)
> + * @apply: atomically apply a new PWM config
>   * @get_state: get the current PWM state. This function is only
>   *            called once per PWM device when the PWM chip is
>   *            registered.
> --
> 2.20.1
>

Re: [PATCH v2 0/6] pwm: mxs: add support for setting polarity via DT

[Thierry Reding]

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On Fri, Oct 04, 2019 at 03:32:01PM +0200, Rasmus Villemoes wrote:
> This series adds support for setting the polarity via DT to the
> pwm-mxs driver.
> 
> The DT binding is updated, but I'm not touching the existing .dts or
> .dtsi files - it seems that the same was done for bcm2835 in commits
> 46421d9d8e802e570dfa4d793a4938d2642ec7a7 and
> 8a88b2a2017d1e7e80db53080baff591fd454722, while
> arch/arm/boot/dts/bcm283x.dtsi still has #pwm-cells = <2>.
> 
> v2:
> - Rebase to v5.4-rc1
> - Address comments from Uwe.
> - Add Rob's ack to patch 4.
> - New patches 5 and 6. The last one is independent of the others, but
>   I stumbled on this when rebasing and found the signature had
>   changed.
> 
> Rasmus Villemoes (6):
>   pwm: mxs: implement ->apply
>   pwm: mxs: remove legacy methods
>   pwm: mxs: add support for inverse polarity
>   dt-bindings: pwm: mxs-pwm: Increase #pwm-cells
>   pwm: mxs: avoid a division in mxs_pwm_apply()
>   pwm: update comment on struct pwm_ops::apply
> 
>  .../devicetree/bindings/pwm/mxs-pwm.txt       |   4 +-
>  drivers/pwm/pwm-mxs.c                         | 101 +++++++++---------
>  include/linux/pwm.h                           |   5 +-
>  3 files changed, 53 insertions(+), 57 deletions(-)

Applied, thanks.

Thierry

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