Messages in this thread | | | Date | Thu, 19 Sep 2013 13:56:53 +0200 | From | Thierry Reding <> | Subject | Re: [PATCH] pwm-backlight: allow for non-increasing brightness levels |
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On Thu, Sep 12, 2013 at 11:35:52AM -0700, Mike Dunn wrote: > Currently the driver assumes that the values specified in the brightness-levels > device tree property increase as they are parsed from left to right. But boards > that invert the signal between the PWM output and the backlight will need to > specify decreasing brightness-levels. This patch removes the assumption that > the last element of the array is the max value, and instead searches the array > for the max value and uses that as the normalizing value when determining the > duty cycle.
"maximum value", "... and uses that as the scale to normalize the duty cycle"?
Also please wrap commit messages at 72 characters.
> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c > index 1fea627..d66aaa0 100644 > --- a/drivers/video/backlight/pwm_bl.c > +++ b/drivers/video/backlight/pwm_bl.c > @@ -27,6 +27,7 @@ struct pwm_bl_data { > unsigned int period; > unsigned int lth_brightness; > unsigned int *levels; > + unsigned int max_level;
Perhaps call this "scale"? Otherwise there some potential to mix it up with max_brightness.
> @@ -195,7 +196,15 @@ static int pwm_backlight_probe(struct platform_device *pdev) > } > > if (data->levels) { > - max = data->levels[data->max_brightness]; > + int i, max_value = 0, max_idx = 0;
i should be unsigned int to match the type of data->max_brightness.
> + for (i = 0; i <= data->max_brightness; i++) {
There should be a blank line above this one to increase readability.
> + if (data->levels[i] > max_value) { > + max_value = data->levels[i]; > + max_idx = i; > + } > + } > + pb->max_level = max_idx;
Some here.
Also I suggest to just drop the max_ prefix from the local variables. Perhaps also simplify all of it to something like:
for (i = 0; i <= data->max_brightness; i++) if (data->levels[i] > pb->scale) pb->scale = data->levels[i];
And get rid of the index altogether. That way you can use pb->scale directly during the computation of the duty cycle and don't have to index the levels array over and over again.
Thierry [unhandled content-type:application/pgp-signature] | |