128 lines
3.6 KiB
Diff
128 lines
3.6 KiB
Diff
From 62689ec6d3317abdc76cf791d5ba0af87811f3c7 Mon Sep 17 00:00:00 2001
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From: Ondrej Jirman <megous@megous.com>
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Date: Mon, 7 Jun 2021 20:27:07 +0200
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Subject: [PATCH 327/478] video: pwm_bl: Allow to change lth_brightness via
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sysfs
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Read minimum duty cycle in % from DT, and allow to change it via
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sysfs.
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Minimum brightness calibration instructions:
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echo 1 > /sys/class/backlight/backlight/brightness
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echo 1 > /sys/class/backlight/backlight/device/lth_brightness
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echo 2 > /sys/class/backlight/backlight/device/lth_brightness
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echo 3 > /sys/class/backlight/backlight/device/lth_brightness
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.... increase values until you like the minimum brightness
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Then make sure to restore this value after each boot by writing it to
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/sys/class/backlight/backlight/device/lth_brightness
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Signed-off-by: Ondrej Jirman <megous@megous.com>
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---
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drivers/video/backlight/pwm_bl.c | 72 +++++++++++++++++++++++++++++++-
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1 file changed, 70 insertions(+), 2 deletions(-)
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diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
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index fff92ccd1b5a..0c6d3be8c204 100644
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--- a/drivers/video/backlight/pwm_bl.c
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+++ b/drivers/video/backlight/pwm_bl.c
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@@ -450,6 +450,61 @@ static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
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return active ? FB_BLANK_UNBLANK: FB_BLANK_POWERDOWN;
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}
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+static ssize_t lth_brightness_show(struct device *dev,
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+ struct device_attribute *attr, char *buf)
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+{
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+ struct backlight_device *bl = platform_get_drvdata(to_platform_device(dev));
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+ struct pwm_bl_data *pb = bl ? bl_get_data(bl) : NULL;
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+ struct pwm_state state;
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+ unsigned val;
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+
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+ if (!pb)
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+ return -EBUSY;
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+
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+ pwm_get_state(pb->pwm, &state);
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+ val = div_u64(100 * pb->lth_brightness, state.period);
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+
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+ return scnprintf(buf, PAGE_SIZE, "%u\n", val);
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+}
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+
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+static ssize_t lth_brightness_store(struct device *dev,
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+ struct device_attribute *attr,
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+ const char *buf, size_t len)
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+{
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+ struct backlight_device *bl = platform_get_drvdata(to_platform_device(dev));
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+ struct pwm_bl_data *pb = bl ? bl_get_data(bl) : NULL;
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+ struct pwm_state state;
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+ unsigned val;
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+ int ret;
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+
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+ if (!pb)
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+ return -EBUSY;
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+
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+ ret = kstrtouint(buf, 10, &val);
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+ if (ret)
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+ return ret;
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+
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+ if (val > 100)
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+ val = 100;
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+
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+ pwm_get_state(pb->pwm, &state);
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+ pb->lth_brightness = div_u64(val * state.period, 100);
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+ pwm_backlight_update_status(bl);
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+
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+ return len;
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+}
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+
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+static DEVICE_ATTR_RW(lth_brightness);
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+
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+static struct attribute *pwm_bl_attrs[] = {
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+ &dev_attr_lth_brightness.attr,
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+ NULL,
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+};
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+
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+static const struct attribute_group pwm_bl_group = {
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+ .attrs = pwm_bl_attrs,
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+};
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+
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static int pwm_backlight_probe(struct platform_device *pdev)
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{
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struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
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@@ -459,6 +514,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
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struct device_node *node = pdev->dev.of_node;
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struct pwm_bl_data *pb;
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struct pwm_state state, state_real;
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+ u32 lth_brightness;
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unsigned int i;
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int ret;
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@@ -600,8 +656,20 @@ static int pwm_backlight_probe(struct platform_device *pdev)
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pb->scale = data->max_brightness;
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}
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- pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
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- pb->scale));
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+ pb->lth_brightness = div_u64(data->lth_brightness * state.period, pb->scale);
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+
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+ ret = of_property_read_u32(pdev->dev.of_node, "lth-brightness",
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+ <h_brightness);
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+ if (ret == 0) {
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+ if (lth_brightness > 100)
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+ lth_brightness = 100;
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+
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+ pb->lth_brightness = div_u64(lth_brightness * state.period, 100);
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+ }
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+
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+ ret = devm_device_add_group(&pdev->dev, &pwm_bl_group);
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+ if (ret)
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+ goto err_alloc;
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props.type = BACKLIGHT_RAW;
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props.max_brightness = data->max_brightness;
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--
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2.35.3
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