Messages in this thread | | | Subject | Re: [PATCH] leds: leds-pca963x: workaround group blink scaling issue | From | Jacek Anaszewski <> | Date | Thu, 13 Oct 2016 16:05:15 +0200 |
| |
Hi Matt,
On 10/13/2016 03:16 PM, Matt Ranostay wrote: > 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.
Why DT property? Is it somehow dependent on the board configuration? How this period-scale value is calculated? Is it inferred empirically?
> 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; > } > >
-- Best regards, Jacek Anaszewski
| |