[PATCHv2 0/2] pwm: imx: support polarity inversion

[PATCHv2 0/2] pwm: imx: support polarity inversion

[Lothar Waßmann]

The first patch does a minor source cleanup without any functional
change.

Changes wrt. v1:
- make PWM_POLARITY flag optional, so that the driver will work
  with either the existing DT binding or with support for polarity
  inversion.

[PATCHv2 1/2] pwm: imx: indentation cleanup

[Lothar Waßmann]

Consistently use TABs for indentation and the same indentation level.
No functional change.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
---
 drivers/pwm/pwm-imx.c |   26 +++++++++++++-------------
 1 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index cc47733..3b00a82 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -21,24 +21,24 @@
 
 /* i.MX1 and i.MX21 share the same PWM function block: */
 
-#define MX1_PWMC    0x00   /* PWM Control Register */
-#define MX1_PWMS    0x04   /* PWM Sample Register */
-#define MX1_PWMP    0x08   /* PWM Period Register */
+#define MX1_PWMC			0x00   /* PWM Control Register */
+#define MX1_PWMS			0x04   /* PWM Sample Register */
+#define MX1_PWMP			0x08   /* PWM Period Register */
 
-#define MX1_PWMC_EN		(1 << 4)
+#define MX1_PWMC_EN			(1 << 4)
 
 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
 
-#define MX3_PWMCR                 0x00    /* PWM Control Register */
-#define MX3_PWMSAR                0x0C    /* PWM Sample Register */
-#define MX3_PWMPR                 0x10    /* PWM Period Register */
-#define MX3_PWMCR_PRESCALER(x)    (((x - 1) & 0xFFF) << 4)
-#define MX3_PWMCR_DOZEEN                (1 << 24)
-#define MX3_PWMCR_WAITEN                (1 << 23)
+#define MX3_PWMCR			0x00   /* PWM Control Register */
+#define MX3_PWMSAR			0x0C   /* PWM Sample Register */
+#define MX3_PWMPR			0x10   /* PWM Period Register */
+#define MX3_PWMCR_PRESCALER(x)		(((x - 1) & 0xFFF) << 4)
+#define MX3_PWMCR_DOZEEN		(1 << 24)
+#define MX3_PWMCR_WAITEN		(1 << 23)
 #define MX3_PWMCR_DBGEN			(1 << 22)
-#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
-#define MX3_PWMCR_CLKSRC_IPG      (1 << 16)
-#define MX3_PWMCR_EN              (1 << 0)
+#define MX3_PWMCR_CLKSRC_IPG_HIGH	(2 << 16)
+#define MX3_PWMCR_CLKSRC_IPG		(1 << 16)
+#define MX3_PWMCR_EN			(1 << 0)
 
 struct imx_chip {
 	struct clk	*clk_per;
-- 
1.7.2.5

[PATCHv2 2/2] pwm: imx: support polarity inversion

[Lothar Waßmann]

The i.MX PWM controller supports inverting the polarity of the PWM
output. Make this feature available in the pxm-imx driver.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
---
 Documentation/devicetree/bindings/pwm/imx-pwm.txt |    5 +-
 drivers/pwm/pwm-imx.c                             |   42 +++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.txt b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
index b50d7a6d..d0b04b5 100644
--- a/Documentation/devicetree/bindings/pwm/imx-pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
@@ -3,8 +3,9 @@ Freescale i.MX PWM controller
 Required properties:
 - compatible: should be "fsl,<soc>-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
-  the cells format.
+- #pwm-cells: may be 2 for backwards compatibility or 3 to support
+  switching the output polarity. See pwm.txt in this directory for a
+  description of the cells format.
 - interrupts: The interrupt for the pwm controller
 
 Example:
diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index 3b00a82..05461bb 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -36,6 +36,7 @@
 #define MX3_PWMCR_DOZEEN		(1 << 24)
 #define MX3_PWMCR_WAITEN		(1 << 23)
 #define MX3_PWMCR_DBGEN			(1 << 22)
+#define MX3_PWMCR_POUTC			(1 << 18)
 #define MX3_PWMCR_CLKSRC_IPG_HIGH	(2 << 16)
 #define MX3_PWMCR_CLKSRC_IPG		(1 << 16)
 #define MX3_PWMCR_EN			(1 << 0)
@@ -138,6 +139,9 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
 	if (test_bit(PWMF_ENABLED, &pwm->flags))
 		cr |= MX3_PWMCR_EN;
 
+	if (pwm->polarity == PWM_POLARITY_INVERSED)
+		cr |= MX3_PWMCR_POUTC;
+
 	writel(cr, imx->mmio_base + MX3_PWMCR);
 
 	return 0;
@@ -155,6 +159,11 @@ static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
 	else
 		val &= ~MX3_PWMCR_EN;
 
+	if (chip->pwms[0].polarity == PWM_POLARITY_INVERSED)
+		val |= MX3_PWMCR_POUTC;
+	else
+		val &= ~MX3_PWMCR_POUTC;
+
 	writel(val, imx->mmio_base + MX3_PWMCR);
 }
 
@@ -198,6 +207,17 @@ static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	clk_disable_unprepare(imx->clk_per);
 }
 
+static int imx_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+				enum pwm_polarity polarity)
+{
+	struct imx_chip *imx = to_imx_chip(chip);
+
+	dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", __func__,
+		polarity == PWM_POLARITY_INVERSED ? "inverted" : "normal");
+
+	return 0;
+}
+
 static struct pwm_ops imx_pwm_ops = {
 	.enable = imx_pwm_enable,
 	.disable = imx_pwm_disable,
@@ -209,6 +229,7 @@ struct imx_pwm_data {
 	int (*config)(struct pwm_chip *chip,
 		struct pwm_device *pwm, int duty_ns, int period_ns);
 	void (*set_enable)(struct pwm_chip *chip, bool enable);
+	unsigned output_polarity:1;
 };
 
 static struct imx_pwm_data imx_pwm_data_v1 = {
@@ -219,6 +240,7 @@ static struct imx_pwm_data imx_pwm_data_v1 = {
 static struct imx_pwm_data imx_pwm_data_v2 = {
 	.config = imx_pwm_config_v2,
 	.set_enable = imx_pwm_set_enable_v2,
+	.output_polarity = 1,
 };
 
 static const struct of_device_id imx_pwm_dt_ids[] = {
@@ -271,6 +293,26 @@ static int imx_pwm_probe(struct platform_device *pdev)
 		return PTR_ERR(imx->mmio_base);
 
 	data = of_id->data;
+	if (data->output_polarity) {
+		const struct device_node *np = pdev->dev.of_node;
+		u32 num_cells;
+
+		dev_dbg(&pdev->dev, "PWM supports output inversion\n");
+		ret = of_property_read_u32(np, "#pwm-cells", &num_cells);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "missing property '#pwm-cells'\n");
+			return ret;
+		}
+		if (num_cells == 3) {
+			imx_pwm_ops.set_polarity = imx_pwm_set_polarity;
+			imx->chip.of_xlate = of_pwm_xlate_with_flags;
+		} else if (num_cells != 2) {
+			dev_err(&pdev->dev, "'#pwm-cells' must be <2> or <3>\n");
+			return -EINVAL;
+		}
+		imx->chip.of_pwm_n_cells = num_cells;
+	}
+
 	imx->config = data->config;
 	imx->set_enable = data->set_enable;
 
-- 
1.7.2.5


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Re: [PATCHv2 2/2] pwm: imx: support polarity inversion

[Sascha Hauer]

On Thu, Jan 16, 2014 at 09:06:25AM +0100, Lothar Waßmann wrote:
> The i.MX PWM controller supports inverting the polarity of the PWM
> output. Make this feature available in the pxm-imx driver.
> 
> Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
> ---
>  Documentation/devicetree/bindings/pwm/imx-pwm.txt |    5 +-
>  drivers/pwm/pwm-imx.c                             |   42 +++++++++++++++++++++
>  2 files changed, 45 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.txt b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
> index b50d7a6d..d0b04b5 100644
> --- a/Documentation/devicetree/bindings/pwm/imx-pwm.txt
> +++ b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
> @@ -3,8 +3,9 @@ Freescale i.MX PWM controller
>  Required properties:
>  - compatible: should be "fsl,<soc>-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
> -  the cells format.
> +- #pwm-cells: may be 2 for backwards compatibility or 3 to support
> +  switching the output polarity. See pwm.txt in this directory for a
> +  description of the cells format.
>  - interrupts: The interrupt for the pwm controller
>  
>  Example:
> diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> index 3b00a82..05461bb 100644
> --- a/drivers/pwm/pwm-imx.c
> +++ b/drivers/pwm/pwm-imx.c
> @@ -36,6 +36,7 @@
>  #define MX3_PWMCR_DOZEEN		(1 << 24)
>  #define MX3_PWMCR_WAITEN		(1 << 23)
>  #define MX3_PWMCR_DBGEN			(1 << 22)
> +#define MX3_PWMCR_POUTC			(1 << 18)
>  #define MX3_PWMCR_CLKSRC_IPG_HIGH	(2 << 16)
>  #define MX3_PWMCR_CLKSRC_IPG		(1 << 16)
>  #define MX3_PWMCR_EN			(1 << 0)
> @@ -138,6 +139,9 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
>  	if (test_bit(PWMF_ENABLED, &pwm->flags))
>  		cr |= MX3_PWMCR_EN;
>  
> +	if (pwm->polarity == PWM_POLARITY_INVERSED)
> +		cr |= MX3_PWMCR_POUTC;
> +
>  	writel(cr, imx->mmio_base + MX3_PWMCR);
>  
>  	return 0;
> @@ -155,6 +159,11 @@ static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
>  	else
>  		val &= ~MX3_PWMCR_EN;
>  
> +	if (chip->pwms[0].polarity == PWM_POLARITY_INVERSED)
> +		val |= MX3_PWMCR_POUTC;
> +	else
> +		val &= ~MX3_PWMCR_POUTC;
> +
>  	writel(val, imx->mmio_base + MX3_PWMCR);
>  }
>  
> @@ -198,6 +207,17 @@ static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  	clk_disable_unprepare(imx->clk_per);
>  }
>  
> +static int imx_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> +				enum pwm_polarity polarity)
> +{
> +	struct imx_chip *imx = to_imx_chip(chip);
> +
> +	dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", __func__,
> +		polarity == PWM_POLARITY_INVERSED ? "inverted" : "normal");
> +
> +	return 0;
> +}
> +
>  static struct pwm_ops imx_pwm_ops = {
>  	.enable = imx_pwm_enable,
>  	.disable = imx_pwm_disable,
> @@ -209,6 +229,7 @@ struct imx_pwm_data {
>  	int (*config)(struct pwm_chip *chip,
>  		struct pwm_device *pwm, int duty_ns, int period_ns);
>  	void (*set_enable)(struct pwm_chip *chip, bool enable);
> +	unsigned output_polarity:1;
>  };
>  
>  static struct imx_pwm_data imx_pwm_data_v1 = {
> @@ -219,6 +240,7 @@ static struct imx_pwm_data imx_pwm_data_v1 = {
>  static struct imx_pwm_data imx_pwm_data_v2 = {
>  	.config = imx_pwm_config_v2,
>  	.set_enable = imx_pwm_set_enable_v2,
> +	.output_polarity = 1,
>  };
>  
>  static const struct of_device_id imx_pwm_dt_ids[] = {
> @@ -271,6 +293,26 @@ static int imx_pwm_probe(struct platform_device *pdev)
>  		return PTR_ERR(imx->mmio_base);
>  
>  	data = of_id->data;
> +	if (data->output_polarity) {
> +		const struct device_node *np = pdev->dev.of_node;
> +		u32 num_cells;
> +
> +		dev_dbg(&pdev->dev, "PWM supports output inversion\n");
> +		ret = of_property_read_u32(np, "#pwm-cells", &num_cells);
> +		if (ret < 0) {
> +			dev_err(&pdev->dev, "missing property '#pwm-cells'\n");
> +			return ret;
> +		}
> +		if (num_cells == 3) {
> +			imx_pwm_ops.set_polarity = imx_pwm_set_polarity;
> +			imx->chip.of_xlate = of_pwm_xlate_with_flags;
> +		} else if (num_cells != 2) {
> +			dev_err(&pdev->dev, "'#pwm-cells' must be <2> or <3>\n");
> +			return -EINVAL;
> +		}
> +		imx->chip.of_pwm_n_cells = num_cells;
> +	}

Can't this be done in the PWM core? Right now the PWM core checks for
of_pwm_n_cells before calling ->of_xlate. IMO this check should be done
in the of_xlate hook. Then of_pwm_simple_xlate and
of_pwm_xlate_with_flags can be merged into something like:

static struct pwm_device *
of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args
*args)
{
	struct pwm_device *pwm;
	int ret;

	if (pc->of_pwm_n_cells < 2)
		return ERR_PTR(-EINVAL);

	if (args->args[0] >= pc->npwm)
		return ERR_PTR(-EINVAL);

	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
	if (IS_ERR(pwm))
		return pwm;

	if (pc->of_pwm_n_cells >= 3) {
		if (args->args[2] & PWM_POLARITY_INVERTED)
			ret = pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
		else
			ret = pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
		if (ret)
			return ret;
	}

	pwm_set_period(pwm, args->args[1]);

	return pwm;
}

Sascha

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Re: [PATCHv2 2/2] pwm: imx: support polarity inversion

[Lothar Waßmann]

Hi,

Sascha Hauer wrote:
> On Thu, Jan 16, 2014 at 09:06:25AM +0100, Lothar Waßmann wrote:
> > The i.MX PWM controller supports inverting the polarity of the PWM
> > output. Make this feature available in the pxm-imx driver.
> > 
> > Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
> > ---
> >  Documentation/devicetree/bindings/pwm/imx-pwm.txt |    5 +-
> >  drivers/pwm/pwm-imx.c                             |   42 +++++++++++++++++++++
> >  2 files changed, 45 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.txt b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
> > index b50d7a6d..d0b04b5 100644
> > --- a/Documentation/devicetree/bindings/pwm/imx-pwm.txt
> > +++ b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
> > @@ -3,8 +3,9 @@ Freescale i.MX PWM controller
> >  Required properties:
> >  - compatible: should be "fsl,<soc>-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
> > -  the cells format.
> > +- #pwm-cells: may be 2 for backwards compatibility or 3 to support
> > +  switching the output polarity. See pwm.txt in this directory for a
> > +  description of the cells format.
> >  - interrupts: The interrupt for the pwm controller
> >  
> >  Example:
> > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> > index 3b00a82..05461bb 100644
> > --- a/drivers/pwm/pwm-imx.c
> > +++ b/drivers/pwm/pwm-imx.c
> > @@ -36,6 +36,7 @@
> >  #define MX3_PWMCR_DOZEEN		(1 << 24)
> >  #define MX3_PWMCR_WAITEN		(1 << 23)
> >  #define MX3_PWMCR_DBGEN			(1 << 22)
> > +#define MX3_PWMCR_POUTC			(1 << 18)
> >  #define MX3_PWMCR_CLKSRC_IPG_HIGH	(2 << 16)
> >  #define MX3_PWMCR_CLKSRC_IPG		(1 << 16)
> >  #define MX3_PWMCR_EN			(1 << 0)
> > @@ -138,6 +139,9 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
> >  	if (test_bit(PWMF_ENABLED, &pwm->flags))
> >  		cr |= MX3_PWMCR_EN;
> >  
> > +	if (pwm->polarity == PWM_POLARITY_INVERSED)
> > +		cr |= MX3_PWMCR_POUTC;
> > +
> >  	writel(cr, imx->mmio_base + MX3_PWMCR);
> >  
> >  	return 0;
> > @@ -155,6 +159,11 @@ static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
> >  	else
> >  		val &= ~MX3_PWMCR_EN;
> >  
> > +	if (chip->pwms[0].polarity == PWM_POLARITY_INVERSED)
> > +		val |= MX3_PWMCR_POUTC;
> > +	else
> > +		val &= ~MX3_PWMCR_POUTC;
> > +
> >  	writel(val, imx->mmio_base + MX3_PWMCR);
> >  }
> >  
> > @@ -198,6 +207,17 @@ static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> >  	clk_disable_unprepare(imx->clk_per);
> >  }
> >  
> > +static int imx_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> > +				enum pwm_polarity polarity)
> > +{
> > +	struct imx_chip *imx = to_imx_chip(chip);
> > +
> > +	dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", __func__,
> > +		polarity == PWM_POLARITY_INVERSED ? "inverted" : "normal");
> > +
> > +	return 0;
> > +}
> > +
> >  static struct pwm_ops imx_pwm_ops = {
> >  	.enable = imx_pwm_enable,
> >  	.disable = imx_pwm_disable,
> > @@ -209,6 +229,7 @@ struct imx_pwm_data {
> >  	int (*config)(struct pwm_chip *chip,
> >  		struct pwm_device *pwm, int duty_ns, int period_ns);
> >  	void (*set_enable)(struct pwm_chip *chip, bool enable);
> > +	unsigned output_polarity:1;
> >  };
> >  
> >  static struct imx_pwm_data imx_pwm_data_v1 = {
> > @@ -219,6 +240,7 @@ static struct imx_pwm_data imx_pwm_data_v1 = {
> >  static struct imx_pwm_data imx_pwm_data_v2 = {
> >  	.config = imx_pwm_config_v2,
> >  	.set_enable = imx_pwm_set_enable_v2,
> > +	.output_polarity = 1,
> >  };
> >  
> >  static const struct of_device_id imx_pwm_dt_ids[] = {
> > @@ -271,6 +293,26 @@ static int imx_pwm_probe(struct platform_device *pdev)
> >  		return PTR_ERR(imx->mmio_base);
> >  
> >  	data = of_id->data;
> > +	if (data->output_polarity) {
> > +		const struct device_node *np = pdev->dev.of_node;
> > +		u32 num_cells;
> > +
> > +		dev_dbg(&pdev->dev, "PWM supports output inversion\n");
> > +		ret = of_property_read_u32(np, "#pwm-cells", &num_cells);
> > +		if (ret < 0) {
> > +			dev_err(&pdev->dev, "missing property '#pwm-cells'\n");
> > +			return ret;
> > +		}
> > +		if (num_cells == 3) {
> > +			imx_pwm_ops.set_polarity = imx_pwm_set_polarity;
> > +			imx->chip.of_xlate = of_pwm_xlate_with_flags;
> > +		} else if (num_cells != 2) {
> > +			dev_err(&pdev->dev, "'#pwm-cells' must be <2> or <3>\n");
> > +			return -EINVAL;
> > +		}
> > +		imx->chip.of_pwm_n_cells = num_cells;
> > +	}
> 
> Can't this be done in the PWM core? Right now the PWM core checks for
> of_pwm_n_cells before calling ->of_xlate. IMO this check should be done
> in the of_xlate hook. Then of_pwm_simple_xlate and
> of_pwm_xlate_with_flags can be merged into something like:
> 
This wouldn't buy much without a material change to of_pwm_get().
The function of_parse_phandle_with_args() called by of_pwm_get()
requires the number of args in the pwms property be greater or equal to
the #pwm-cells property in the pwm node. Thus, the interesting case of
having #pwm-cells = <3> without changing the existing users is
prohibited by of_parse_phandle_with_args().

of_pwm_get() would have to be changed to something like below to allow
this:
struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
{
	struct pwm_device *pwm = NULL;
	struct of_phandle_args args;
	struct pwm_chip *pc;
	int index = 0;
	int err;
	struct property *prop;
	u32 num_cells;
	int i;
	const __be32 *list;

	if (con_id) {
		index = of_property_match_string(np, "pwm-names", con_id);
		if (index < 0)
			return ERR_PTR(index);
	}

	args.np = of_parse_phandle(np, "pwms", index);
	if (!args.np) {
		pr_err("%s(): property 'pwms' not found in '%s'\n",
			__func__, np->full_name);
		return ERR_PTR(-ENOENT);
	}

	err = of_property_read_u32(args.np, "#pwm-cells", &num_cells);
	if (err) {
		pr_err("%s(): could not read property '#pwm-cells' in '%s': %d\n",
			__func__, args.np->full_name, err);
		return ERR_PTR(err);
	}

	prop = of_find_property(np, "pwms", NULL);
	if (WARN_ON(!prop))
		return ERR_PTR(-EINVAL);

	args.args_count = prop->length / sizeof(u32) - 1;
	list = prop->value;
	for (i = 0; i < args.args_count; i++)
		args.args[i] = be32_to_cpup(++list);

	pc = of_node_to_pwmchip(args.np);
	if (IS_ERR(pc)) {
		pr_err("%s(): PWM chip not found\n", __func__);
		pwm = ERR_CAST(pc);
		goto put;
	}
[...]

 

Lothar Waßmann
-- 
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info@karo-electronics.de
___________________________________________________________

Re: [PATCHv2 2/2] pwm: imx: support polarity inversion

[Russell King - ARM Linux]

On Thu, Jan 23, 2014 at 08:37:14AM +0100, Lothar Waßmann wrote:
> This wouldn't buy much without a material change to of_pwm_get().
> The function of_parse_phandle_with_args() called by of_pwm_get()
> requires the number of args in the pwms property be greater or equal to
> the #pwm-cells property in the pwm node. Thus, the interesting case of
> having #pwm-cells = <3> without changing the existing users is
> prohibited by of_parse_phandle_with_args().

I really don't think that's a problem we need to be concerned with at
the moment.  What we need is for the kernel to be able to parse files
with #pwm-cells = <2> with the pwms property containing two arguments,
and when they're updated to #pwm-cells = <3> with the pwms property
containing three arguments.

Yes, that means all the board dt files need to be updated at the same
time to include the additional argument, but I don't see that as a big
problem.

What we do need to do is to adjust the PWM parsing code such that it's
possible to use either specification without causing any side effects.

I would test this, but as u-boot is rather fscked at the moment and the
networking has broken on my cubox-i as a result... and it seems that the
u-boot developers have pissed off cubox-i u-boot hackers soo much that
they've dropped u-boot in favour of barebox...

 drivers/pwm/core.c  | 59 +++++++++++++++++++++++++++++------------------------
 include/linux/pwm.h |  2 ++
 2 files changed, 34 insertions(+), 27 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 2ca95042a0b9..40adbce8ef0c 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -132,14 +132,11 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 }
 
 struct pwm_device *
-of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
+of_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 {
 	struct pwm_device *pwm;
 
-	if (pc->of_pwm_n_cells < 3)
-		return ERR_PTR(-EINVAL);
-
-	if (args->args[0] >= pc->npwm)
+	if (args->args_count < 2)
 		return ERR_PTR(-EINVAL);
 
 	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
@@ -148,33 +145,45 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
 
 	pwm_set_period(pwm, args->args[1]);
 
-	if (args->args[2] & PWM_POLARITY_INVERTED)
-		pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
-	else
-		pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
+	if (args->args_count > 2) {
+		int err;
+
+		if (args->args[2] & PWM_POLARITY_INVERTED)
+			err = pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
+		else
+			err = pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
+
+		pwm_put(pwm);
+		return ERR_PTR(err);
+	}
 
 	return pwm;
 }
+EXPORT_SYMBOL(of_pwm_xlate);
+
+struct pwm_device *
+of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+	if (pc->of_pwm_n_cells < 3)
+		return ERR_PTR(-EINVAL);
+
+	if (args->args_count != pc->of_pwm_n_cells)
+		return ERR_PTR(-EINVAL);
+
+	return of_pwm_xlate(pc, args);
+}
 EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);
 
 static struct pwm_device *
 of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 {
-	struct pwm_device *pwm;
-
 	if (pc->of_pwm_n_cells < 2)
 		return ERR_PTR(-EINVAL);
 
-	if (args->args[0] >= pc->npwm)
+	if (args->args_count != pc->of_pwm_n_cells)
 		return ERR_PTR(-EINVAL);
 
-	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
-	if (IS_ERR(pwm))
-		return pwm;
-
-	pwm_set_period(pwm, args->args[1]);
-
-	return pwm;
+	return of_pwm_xlate(pc, args);
 }
 
 static void of_pwmchip_add(struct pwm_chip *chip)
@@ -536,16 +545,12 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
 		goto put;
 	}
 
-	if (args.args_count != pc->of_pwm_n_cells) {
-		pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name,
-			 args.np->full_name);
-		pwm = ERR_PTR(-EINVAL);
-		goto put;
-	}
-
 	pwm = pc->of_xlate(pc, &args);
-	if (IS_ERR(pwm))
+	if (IS_ERR(pwm)) {
+		pr_debug("%s: of_xlate failed for %s: %d\n", np->full_name,
+			 args.np->full_name, (int)PTR_ERR(pwm));
 		goto put;
+	}
 
 	/*
 	 * If a consumer name was not given, try to look it up from the
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index f0feafd184a0..14a823f77c31 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -188,6 +188,8 @@ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 					 unsigned int index,
 					 const char *label);
 
+struct pwm_device *of_pwm_xlate(struct pwm_chip *pc,
+		const struct of_phandle_args *args);
 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 		const struct of_phandle_args *args);
 


-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".

Re: [PATCHv2 2/2] pwm: imx: support polarity inversion

[Russell King - ARM Linux]

On Thu, Jan 23, 2014 at 11:52:03AM +0000, Russell King - ARM Linux wrote:
> On Thu, Jan 23, 2014 at 08:37:14AM +0100, Lothar Waßmann wrote:
> > This wouldn't buy much without a material change to of_pwm_get().
> > The function of_parse_phandle_with_args() called by of_pwm_get()
> > requires the number of args in the pwms property be greater or equal to
> > the #pwm-cells property in the pwm node. Thus, the interesting case of
> > having #pwm-cells = <3> without changing the existing users is
> > prohibited by of_parse_phandle_with_args().
> 
> I really don't think that's a problem we need to be concerned with at
> the moment.  What we need is for the kernel to be able to parse files
> with #pwm-cells = <2> with the pwms property containing two arguments,
> and when they're updated to #pwm-cells = <3> with the pwms property
> containing three arguments.
> 
> Yes, that means all the board dt files need to be updated at the same
> time to include the additional argument, but I don't see that as a big
> problem.
> 
> What we do need to do is to adjust the PWM parsing code such that it's
> possible to use either specification without causing any side effects.
> 
> I would test this, but as u-boot is rather fscked at the moment and the
> networking has broken on my cubox-i as a result... and it seems that the
> u-boot developers have pissed off cubox-i u-boot hackers soo much that
> they've dropped u-boot in favour of barebox...

Oh, and another reason... the u-boot video settings are totally and utterly
buggered to the point that it doesn't produce correct timings, and it seems
that u-boot people have zero interest in fixing that, so u-boot mainline is
basically refusing to fix this - another reason to stay away from it.

(1024x768 @ 60Hz produces 70Hz refresh on iMX6Q here - I've seen it produce
51Hz on iMX6S, both of which are far enough out that lots of display devices
will not accept it as a valid signal.)

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".

Re: [PATCHv2 2/2] pwm: imx: support polarity inversion

[Russell King - ARM Linux]

On Thu, Jan 23, 2014 at 11:52:03AM +0000, Russell King - ARM Linux wrote:
> On Thu, Jan 23, 2014 at 08:37:14AM +0100, Lothar Waßmann wrote:
> > This wouldn't buy much without a material change to of_pwm_get().
> > The function of_parse_phandle_with_args() called by of_pwm_get()
> > requires the number of args in the pwms property be greater or equal to
> > the #pwm-cells property in the pwm node. Thus, the interesting case of
> > having #pwm-cells = <3> without changing the existing users is
> > prohibited by of_parse_phandle_with_args().
> 
> I really don't think that's a problem we need to be concerned with at
> the moment.  What we need is for the kernel to be able to parse files
> with #pwm-cells = <2> with the pwms property containing two arguments,
> and when they're updated to #pwm-cells = <3> with the pwms property
> containing three arguments.
> 
> Yes, that means all the board dt files need to be updated at the same
> time to include the additional argument, but I don't see that as a big
> problem.
> 
> What we do need to do is to adjust the PWM parsing code such that it's
> possible to use either specification without causing any side effects.
> 
> I would test this, but as u-boot is rather fscked at the moment and the
> networking has broken on my cubox-i as a result... and it seems that the
> u-boot developers have pissed off cubox-i u-boot hackers soo much that
> they've dropped u-boot in favour of barebox...

Okay, finally confirmed that this works with #pwm-cells = 2.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".