Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'backlight-next-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight
Pull backlight updates from Lee Jones:
"New Functionality:
- Provide support for ACPI enumeration; gpio_backlight
Fix-ups:
- SPDX fixups; pwm_bl
- Fix linear brightness levels to include number available; pwm_bl"
* tag 'backlight-next-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
backlight: pwm_bl: Fix heuristic to determine number of brightness levels
backlight: gpio_backlight: Enable ACPI enumeration
backlight: pwm_bl: Convert to use SPDX identifier
+17
-36
+9
-14
drivers/video/backlight/gpio_backlight.c
+9
-14
drivers/video/backlight/gpio_backlight.c
···
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#include <linux/of_gpio.h>
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#include <linux/platform_data/gpio_backlight.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/slab.h>
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struct gpio_backlight {
···
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struct gpio_backlight *gbl)
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{
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struct device *dev = &pdev->dev;
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struct device_node *np = dev->of_node;
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enum gpiod_flags flags;
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int ret;
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gbl->def_value = of_property_read_bool(np, "default-on");
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gbl->def_value = device_property_read_bool(dev, "default-on");
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flags = gbl->def_value ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
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gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
···
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struct backlight_properties props;
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struct backlight_device *bl;
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struct gpio_backlight *gbl;
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struct device_node *np = pdev->dev.of_node;
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int ret;
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if (!pdata && !np) {
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dev_err(&pdev->dev,
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"failed to find platform data or device tree node.\n");
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return -ENODEV;
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}
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gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
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if (gbl == NULL)
···
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gbl->dev = &pdev->dev;
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-
if (np) {
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if (pdev->dev.fwnode) {
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ret = gpio_backlight_probe_dt(pdev, gbl);
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if (ret)
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return ret;
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} else {
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} else if (pdata) {
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/*
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* Legacy platform data GPIO retrieveal. Do not expand
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* the use of this code path, currently only used by one
···
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gbl->gpiod = gpio_to_desc(pdata->gpio);
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if (!gbl->gpiod)
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return -EINVAL;
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} else {
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dev_err(&pdev->dev,
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"failed to find platform data or device tree node.\n");
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return -ENODEV;
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}
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memset(&props, 0, sizeof(props));
···
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return 0;
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}
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-
#ifdef CONFIG_OF
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static struct of_device_id gpio_backlight_of_match[] = {
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{ .compatible = "gpio-backlight" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
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#endif
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static struct platform_driver gpio_backlight_driver = {
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.driver = {
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.name = "gpio-backlight",
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.of_match_table = of_match_ptr(gpio_backlight_of_match),
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.of_match_table = gpio_backlight_of_match,
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},
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.probe = gpio_backlight_probe,
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};
+8
-22
drivers/video/backlight/pwm_bl.c
+8
-22
drivers/video/backlight/pwm_bl.c
···
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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* 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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struct platform_pwm_backlight_data *data,
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unsigned int period)
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{
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unsigned int counter = 0;
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unsigned int i, n;
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unsigned int i;
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u64 retval;
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/*
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* Count the number of bits needed to represent the period number. The
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* number of bits is used to calculate the number of levels used for the
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* brightness-levels table, the purpose of this calculation is have a
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* pre-computed table with enough levels to get linear brightness
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* perception. The period is divided by the number of bits so for a
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* 8-bit PWM we have 255 / 8 = 32 brightness levels or for a 16-bit PWM
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* we have 65535 / 16 = 4096 brightness levels.
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*
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* Note that this method is based on empirical testing on different
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* devices with PWM of 8 and 16 bits of resolution.
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* Once we have 4096 levels there's little point going much higher...
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* neither interactive sliders nor animation benefits from having
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* more values in the table.
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*/
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n = period;
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while (n) {
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counter += n % 2;
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n >>= 1;
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}
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data->max_brightness =
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min((int)DIV_ROUND_UP(period, fls(period)), 4096);
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data->max_brightness = DIV_ROUND_UP(period, counter);
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data->levels = devm_kcalloc(dev, data->max_brightness,
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sizeof(*data->levels), GFP_KERNEL);
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if (!data->levels)
···
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module_platform_driver(pwm_backlight_driver);
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MODULE_DESCRIPTION("PWM based Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:pwm-backlight");