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Subject[PATCH] leds: leds-pca963x: workaround group blink scaling issue
Date
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.

Cc: Tony Lindgren <tony@atomide.com>
Cc: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
---
Documentation/devicetree/bindings/leds/pca963x.txt | 3 +++
drivers/leds/leds-pca963x.c | 18 +++++++++++++++---
2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/pca963x.txt b/Documentation/devicetree/bindings/leds/pca963x.txt
index dafbe9931c2b..dfbdb123a9bf 100644
--- a/Documentation/devicetree/bindings/leds/pca963x.txt
+++ b/Documentation/devicetree/bindings/leds/pca963x.txt
@@ -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.

diff --git a/drivers/leds/leds-pca963x.c b/drivers/leds/leds-pca963x.c
index 407eba11e187..b6ce1f2ec33e 100644
--- a/drivers/leds/leds-pca963x.c
+++ b/drivers/leds/leds-pca963x.c
@@ -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;
}

--
2.7.4
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