Dear all,

Dear Lothar, Stefan,

quoted

This patch ports "pwm: imx: support output polarity inversion" patch
set written by Lothar Wassmann (v6 from 10.2014).

I've read the e-mail from Stefan regarding missing support for pwm-imx
polarity inversion feature.

I also would like to see it in ML. Hence, my patch. Lothar, please
feel free to squash it to your patches when you (I hope :-) ) will
prepare v7 of this feature.

I hope that this would help.

Was there any decision about those patches?

Would they be included to main line anytime soon?

Best regards,
?ukasz Majewski

Best regards,
?ukasz Majewski

quoted

It is used to control backlight of panels via inverted PWM signal.

The "inversion" of PWM output is not an issue at such devices, since
separate GPIO pin is responsible for enabling and disabling the
panel's backlight.

This patch should be put on top of:

https://patchwork.kernel.org/patch/5065841/
https://patchwork.kernel.org/patch/5065821/
https://patchwork.kernel.org/patch/5065811/


Signed-off-by: Lukasz Majewski <redacted>
---
 drivers/pwm/pwm-imx.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index 471a99e..c37d223 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c

@@ -181,7 +181,7 @@ static int imx_pwm_config_v2(struct pwm_chip

*chip, if (enable)
 		cr |= MX3_PWMCR_EN;
 
-	if (pwm->polarity == PWM_POLARITY_INVERSED)
+	if (pwm->args.polarity == PWM_POLARITY_INVERSED)
 		cr |= MX3_PWMCR_POUTC;
 
 	writel(cr, imx->mmio_base + MX3_PWMCR);

@@ -201,11 +201,6 @@ 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);
 }
 

@@ -253,6 +248,19 @@ 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);
+	u32 val;
+
+	if (polarity == pwm->args.polarity)
+		return 0;
+
+	val = readl(imx->mmio_base + MX3_PWMCR);
+
+	if (polarity == PWM_POLARITY_INVERSED)
+		val |= MX3_PWMCR_POUTC;
+	else
+		val &= ~MX3_PWMCR_POUTC;
+
+	writel(val, imx->mmio_base + MX3_PWMCR);
 
 	dev_dbg(imx->chip.dev, "%s: polarity set to %s\n",
__func__, polarity == PWM_POLARITY_INVERSED ? "inverted" :
"normal");

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