The PWM device provided by Chrome OS EC doesn't really support anything other than setting a relative duty cycle. To support it as a backlight, this patch makes the PWM period optional in the device tree and pretends the valid brightness range is its period_ns.
Signed-off-by: Alper Nebi Yasak <[email protected]> --- drivers/video/pwm_backlight.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/video/pwm_backlight.c b/drivers/video/pwm_backlight.c index 468a5703bd..4c2a307462 100644 --- a/drivers/video/pwm_backlight.c +++ b/drivers/video/pwm_backlight.c @@ -62,10 +62,17 @@ static int set_pwm(struct pwm_backlight_priv *priv) uint duty_cycle; int ret; - duty_cycle = priv->period_ns * (priv->cur_level - priv->min_level) / - (priv->max_level - priv->min_level + 1); - ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns, - duty_cycle); + if (priv->period_ns) { + duty_cycle = priv->period_ns * (priv->cur_level - priv->min_level) / + (priv->max_level - priv->min_level + 1); + ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns, + duty_cycle); + } else { + /* PWM driver will internally scale these like the above. */ + ret = pwm_set_config(priv->pwm, priv->channel, + priv->max_level - priv->min_level + 1, + priv->cur_level - priv->min_level); + } if (ret) return log_ret(ret); @@ -213,10 +220,11 @@ static int pwm_backlight_ofdata_to_platdata(struct udevice *dev) log_debug("Cannot get PWM: ret=%d\n", ret); return log_ret(ret); } - if (args.args_count < 2) + if (args.args_count < 1) return log_msg_ret("Not enough arguments to pwm\n", -EINVAL); priv->channel = args.args[0]; - priv->period_ns = args.args[1]; + if (args.args_count > 1) + priv->period_ns = args.args[1]; if (args.args_count > 2) priv->polarity = args.args[2]; -- 2.28.0
