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![Robert Morell](/assets/img/avatar_default.png)
In systems with multiple framebuffer devices, one of the devices might be blanked while another is unblanked. In order for the backlight blanking logic to know whether to turn off the backlight for a particular framebuffer's blanking notification, it needs to be able to check if a given framebuffer device corresponds to the backlight. This plumbs the check_fb hook from core backlight through the pwm_backlight helper to allow platform code to plug in a check_fb hook. Signed-off-by: Robert Morell <rmorell@nvidia.com> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Arun Murthy <arun.murthy@stericsson.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
216 lines
5.2 KiB
C
216 lines
5.2 KiB
C
/*
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* linux/drivers/video/backlight/pwm_bl.c
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*
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* simple PWM based backlight control, board code has to setup
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* 1) pin configuration so PWM waveforms can output
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* 2) platform_data being correctly configured
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/fb.h>
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/pwm.h>
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#include <linux/pwm_backlight.h>
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#include <linux/slab.h>
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struct pwm_bl_data {
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struct pwm_device *pwm;
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struct device *dev;
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unsigned int period;
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unsigned int lth_brightness;
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int (*notify)(struct device *,
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int brightness);
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int (*check_fb)(struct device *, struct fb_info *);
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};
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static int pwm_backlight_update_status(struct backlight_device *bl)
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{
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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int brightness = bl->props.brightness;
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int max = bl->props.max_brightness;
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if (bl->props.power != FB_BLANK_UNBLANK)
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brightness = 0;
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if (bl->props.fb_blank != FB_BLANK_UNBLANK)
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brightness = 0;
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if (pb->notify)
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brightness = pb->notify(pb->dev, brightness);
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if (brightness == 0) {
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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} else {
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brightness = pb->lth_brightness +
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(brightness * (pb->period - pb->lth_brightness) / max);
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pwm_config(pb->pwm, brightness, pb->period);
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pwm_enable(pb->pwm);
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}
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return 0;
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}
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static int pwm_backlight_get_brightness(struct backlight_device *bl)
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{
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return bl->props.brightness;
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}
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static int pwm_backlight_check_fb(struct backlight_device *bl,
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struct fb_info *info)
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{
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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return !pb->check_fb || pb->check_fb(pb->dev, info);
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}
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static const struct backlight_ops pwm_backlight_ops = {
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.update_status = pwm_backlight_update_status,
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.get_brightness = pwm_backlight_get_brightness,
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.check_fb = pwm_backlight_check_fb,
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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 backlight_properties props;
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struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
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struct backlight_device *bl;
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struct pwm_bl_data *pb;
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int ret;
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if (!data) {
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dev_err(&pdev->dev, "failed to find platform data\n");
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return -EINVAL;
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}
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if (data->init) {
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ret = data->init(&pdev->dev);
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if (ret < 0)
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return ret;
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}
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pb = kzalloc(sizeof(*pb), GFP_KERNEL);
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if (!pb) {
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dev_err(&pdev->dev, "no memory for state\n");
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ret = -ENOMEM;
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goto err_alloc;
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}
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pb->period = data->pwm_period_ns;
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pb->notify = data->notify;
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pb->check_fb = data->check_fb;
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pb->lth_brightness = data->lth_brightness *
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(data->pwm_period_ns / data->max_brightness);
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pb->dev = &pdev->dev;
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pb->pwm = pwm_request(data->pwm_id, "backlight");
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if (IS_ERR(pb->pwm)) {
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dev_err(&pdev->dev, "unable to request PWM for backlight\n");
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ret = PTR_ERR(pb->pwm);
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goto err_pwm;
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} else
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dev_dbg(&pdev->dev, "got pwm for backlight\n");
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memset(&props, 0, sizeof(struct backlight_properties));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = data->max_brightness;
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bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
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&pwm_backlight_ops, &props);
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if (IS_ERR(bl)) {
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dev_err(&pdev->dev, "failed to register backlight\n");
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ret = PTR_ERR(bl);
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goto err_bl;
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}
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bl->props.brightness = data->dft_brightness;
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backlight_update_status(bl);
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platform_set_drvdata(pdev, bl);
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return 0;
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err_bl:
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pwm_free(pb->pwm);
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err_pwm:
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kfree(pb);
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err_alloc:
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if (data->exit)
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data->exit(&pdev->dev);
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return ret;
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}
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static int pwm_backlight_remove(struct platform_device *pdev)
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{
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struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
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struct backlight_device *bl = platform_get_drvdata(pdev);
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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backlight_device_unregister(bl);
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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pwm_free(pb->pwm);
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kfree(pb);
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if (data->exit)
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data->exit(&pdev->dev);
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return 0;
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}
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#ifdef CONFIG_PM
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static int pwm_backlight_suspend(struct platform_device *pdev,
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pm_message_t state)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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if (pb->notify)
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pb->notify(pb->dev, 0);
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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return 0;
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}
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static int pwm_backlight_resume(struct platform_device *pdev)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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backlight_update_status(bl);
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return 0;
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}
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#else
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#define pwm_backlight_suspend NULL
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#define pwm_backlight_resume NULL
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#endif
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static struct platform_driver pwm_backlight_driver = {
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.driver = {
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.name = "pwm-backlight",
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.owner = THIS_MODULE,
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},
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.probe = pwm_backlight_probe,
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.remove = pwm_backlight_remove,
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.suspend = pwm_backlight_suspend,
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.resume = pwm_backlight_resume,
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};
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static int __init pwm_backlight_init(void)
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{
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return platform_driver_register(&pwm_backlight_driver);
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}
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module_init(pwm_backlight_init);
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static void __exit pwm_backlight_exit(void)
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{
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platform_driver_unregister(&pwm_backlight_driver);
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}
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module_exit(pwm_backlight_exit);
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MODULE_DESCRIPTION("PWM based Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:pwm-backlight");
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