[PATCH v2 20/30] video: backlight: fix pwm's duty cycle calculation
Dario Binacchi
dariobin at libero.it
Sun Sep 6 14:11:50 CEST 2020
For levels equal to the maximum value, the duty cycle must be equal to
the period.
Signed-off-by: Dario Binacchi <dariobin at libero.it>
Reviewed-by: Simon Glass <sjg at chromium.org>
---
(no changes since v1)
drivers/video/pwm_backlight.c | 2 +-
test/dm/panel.c | 12 ++++++------
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/video/pwm_backlight.c b/drivers/video/pwm_backlight.c
index 468a5703bd..199ccc030f 100644
--- a/drivers/video/pwm_backlight.c
+++ b/drivers/video/pwm_backlight.c
@@ -63,7 +63,7 @@ static int set_pwm(struct pwm_backlight_priv *priv)
int ret;
duty_cycle = priv->period_ns * (priv->cur_level - priv->min_level) /
- (priv->max_level - priv->min_level + 1);
+ (priv->max_level - priv->min_level);
ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
duty_cycle);
if (ret)
diff --git a/test/dm/panel.c b/test/dm/panel.c
index a840fb4951..49f5ac7169 100644
--- a/test/dm/panel.c
+++ b/test/dm/panel.c
@@ -40,7 +40,7 @@ static int dm_test_panel(struct unit_test_state *uts)
ut_assertok(sandbox_pwm_get_config(pwm, 0, &period_ns, &duty_ns,
&enable, &polarity));
ut_asserteq(1000, period_ns);
- ut_asserteq(170 * 1000 / 256, duty_ns);
+ ut_asserteq(170 * 1000 / 255, duty_ns);
ut_asserteq(true, enable);
ut_asserteq(false, polarity);
ut_asserteq(1, sandbox_gpio_get_value(gpio, 1));
@@ -49,29 +49,29 @@ static int dm_test_panel(struct unit_test_state *uts)
ut_assertok(panel_set_backlight(dev, 40));
ut_assertok(sandbox_pwm_get_config(pwm, 0, &period_ns, &duty_ns,
&enable, &polarity));
- ut_asserteq(64 * 1000 / 256, duty_ns);
+ ut_asserteq(64 * 1000 / 255, duty_ns);
ut_assertok(panel_set_backlight(dev, BACKLIGHT_MAX));
ut_assertok(sandbox_pwm_get_config(pwm, 0, &period_ns, &duty_ns,
&enable, &polarity));
- ut_asserteq(255 * 1000 / 256, duty_ns);
+ ut_asserteq(255 * 1000 / 255, duty_ns);
ut_assertok(panel_set_backlight(dev, BACKLIGHT_MIN));
ut_assertok(sandbox_pwm_get_config(pwm, 0, &period_ns, &duty_ns,
&enable, &polarity));
- ut_asserteq(0 * 1000 / 256, duty_ns);
+ ut_asserteq(0 * 1000 / 255, duty_ns);
ut_asserteq(1, sandbox_gpio_get_value(gpio, 1));
ut_assertok(panel_set_backlight(dev, BACKLIGHT_DEFAULT));
ut_assertok(sandbox_pwm_get_config(pwm, 0, &period_ns, &duty_ns,
&enable, &polarity));
ut_asserteq(true, enable);
- ut_asserteq(170 * 1000 / 256, duty_ns);
+ ut_asserteq(170 * 1000 / 255, duty_ns);
ut_assertok(panel_set_backlight(dev, BACKLIGHT_OFF));
ut_assertok(sandbox_pwm_get_config(pwm, 0, &period_ns, &duty_ns,
&enable, &polarity));
- ut_asserteq(0 * 1000 / 256, duty_ns);
+ ut_asserteq(0 * 1000 / 255, duty_ns);
ut_asserteq(0, sandbox_gpio_get_value(gpio, 1));
ut_asserteq(false, regulator_get_enable(reg));
--
2.17.1
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