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Commit 35c7d301 authored by Matt Ranostay's avatar Matt Ranostay Committed by Jacek Anaszewski
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leds: pca963x: workaround group blink scaling issue 



PCA9632TK part seems to incorrectly blink at ~1.3x of the programmed
rate. This patchset add a nxp,period-scale devicetree property to
adjust for this misconfiguration.

Signed-off-by: default avatarMatt Ranostay <matt@ranostay.consulting>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: default avatarJacek Anaszewski <j.anaszewski@samsung.com>
parent ed25e9ca

Documentation/devicetree/bindings/leds/pca963x.txt

+3 −0
Original line number Diff line number Diff line
@@ -7,6 +7,9 @@ Optional properties: 
- nxp,totem-pole : use totem pole (push-pull) instead of open-drain (pca9632 defaults

  to open-drain, newer chips to totem pole)

- nxp,hw-blink : use hardware blinking instead of software blinking

- nxp,period-scale : In some configurations, the chip blinks faster than expected.

		     This parameter provides a scaling ratio (fixed point, decimal divided

		     by 1000) to compensate, e.g. 1300=1.3x and 750=0.75x.



Each led is represented as a sub-node of the nxp,pca963x device.

drivers/leds/leds-pca963x.c

+15 −3
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ struct pca963x_chipdef { 
	u8			grpfreq;

	u8			ledout_base;

	int			n_leds;

	unsigned int		scaling;

};



static struct pca963x_chipdef pca963x_chipdefs[] = {
@@ -189,6 +190,14 @@ static int pca963x_led_set(struct led_classdev *led_cdev, 
	return pca963x_brightness(pca963x, value);

}



static unsigned int pca963x_period_scale(struct pca963x_led *pca963x,

	unsigned int val)

{

	unsigned int scaling = pca963x->chip->chipdef->scaling;



	return scaling ? DIV_ROUND_CLOSEST(val * scaling, 1000) : val;

}



static int pca963x_blink_set(struct led_classdev *led_cdev,

		unsigned long *delay_on, unsigned long *delay_off)

{
@@ -207,14 +216,14 @@ static int pca963x_blink_set(struct led_classdev *led_cdev, 
		time_off = 500;

	}



	period = time_on + time_off;

	period = pca963x_period_scale(pca963x, time_on + time_off);



	/* If period not supported by hardware, default to someting sane. */

	if ((period < PCA963X_BLINK_PERIOD_MIN) ||

	    (period > PCA963X_BLINK_PERIOD_MAX)) {

		time_on = 500;

		time_off = 500;

		period = time_on + time_off;

		period = pca963x_period_scale(pca963x, 1000);

	}



	/*
@@ -222,7 +231,7 @@ static int pca963x_blink_set(struct led_classdev *led_cdev, 
	 *	(time_on / period) = (GDC / 256) ->

	 *		GDC = ((time_on * 256) / period)

	 */

	gdc = (time_on * 256) / period;

	gdc = (pca963x_period_scale(pca963x, time_on) * 256) / period;



	/*

	 * From manual: period = ((GFRQ + 1) / 24) in seconds.
@@ -294,6 +303,9 @@ pca963x_dt_init(struct i2c_client *client, struct pca963x_chipdef *chip) 
	else

		pdata->blink_type = PCA963X_SW_BLINK;



	if (of_property_read_u32(np, "nxp,period-scale", &chip->scaling))

		chip->scaling = 1000;



	return pdata;

}