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| author | Alper Nebi Yasak <alpernebiyasak@gmail.com> | 2020-10-22 23:49:26 +0300 |
|---|---|---|
| committer | Anatolij Gustschin <agust@denx.de> | 2021-04-10 16:07:12 +0200 |
| commit | fefa713b1843cf13d3132bfe0cf27710938c5d92 (patch) | |
| tree | 4ae09212a60da99436d30eb24b3f9d041553cdbe /drivers | |
| parent | 9749d2ea29e1a535c9ea8f850db8b6abe6df7b15 (diff) | |
| download | u-boot-fefa713b1843cf13d3132bfe0cf27710938c5d92.zip u-boot-fefa713b1843cf13d3132bfe0cf27710938c5d92.tar.gz u-boot-fefa713b1843cf13d3132bfe0cf27710938c5d92.tar.bz2 | |
video: backlight: Support PWMs without a known period_ns
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.
Also adds a sandbox test for a PWM channel that has a fixed period,
checking that the resulting duty_cycle matches on a set_config() even if
the requested period_ns can't be set.
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/pwm/sandbox_pwm.c | 11 | ||||
| -rw-r--r-- | drivers/video/pwm_backlight.c | 20 |
2 files changed, 23 insertions, 8 deletions
diff --git a/drivers/pwm/sandbox_pwm.c b/drivers/pwm/sandbox_pwm.c index 318dce7..4df15f0 100644 --- a/drivers/pwm/sandbox_pwm.c +++ b/drivers/pwm/sandbox_pwm.c @@ -59,8 +59,15 @@ static int sandbox_pwm_set_config(struct udevice *dev, uint channel, if (channel >= NUM_CHANNELS) return -ENOSPC; chan = &priv->chan[channel]; - chan->period_ns = period_ns; - chan->duty_ns = duty_ns; + + if (channel == 2) { + /* Pretend to have some fixed period */ + chan->period_ns = 4096; + chan->duty_ns = duty_ns * 4096 / period_ns; + } else { + chan->period_ns = period_ns; + chan->duty_ns = duty_ns; + } return 0; } diff --git a/drivers/video/pwm_backlight.c b/drivers/video/pwm_backlight.c index 9e32bc4..4c86215 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); - 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); + 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, + priv->cur_level - priv->min_level); + } if (ret) return log_ret(ret); @@ -213,10 +220,11 @@ static int pwm_backlight_of_to_plat(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]; |