Merge tag 'backlight-next-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee...

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

diff --combined drivers/video/backlight/gpio_backlight.c
index b9300f3e1ee6397eb6ba768630eb84d5dd98288f,05c12df62b27ce41198f22fd57f90d89c8c2e1b4..e84f3087e29fc10f5a269412066caae4208255e7
--- 1/drivers/video/backlight/gpio_backlight.c
--- 2/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@@ -1,6 -1,9 +1,6 @@@
 +// SPDX-License-Identifier: GPL-2.0-only
  /*
   * gpio_backlight.c - Simple GPIO-controlled backlight
 - *
 - * This program is free software; you can redistribute it and/or modify
 - * it under the terms of the GNU General Public License version 2 as
 - * published by the Free Software Foundation.
   */
  
  #include <linux/backlight.h>
@@@ -15,6 -18,7 +15,7 @@@
  #include <linux/of_gpio.h>
  #include <linux/platform_data/gpio_backlight.h>
  #include <linux/platform_device.h>
+ #include <linux/property.h>
  #include <linux/slab.h>
  
  struct gpio_backlight {
@@@ -58,11 -62,10 +59,10 @@@ static int gpio_backlight_probe_dt(stru
                                   struct gpio_backlight *gbl)
  {
        struct device *dev = &pdev->dev;
-       struct device_node *np = dev->of_node;
        enum gpiod_flags flags;
        int ret;
  
-       gbl->def_value = of_property_read_bool(np, "default-on");
+       gbl->def_value = device_property_read_bool(dev, "default-on");
        flags = gbl->def_value ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
  
        gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
@@@ -86,26 -89,19 +86,19 @@@ static int gpio_backlight_probe(struct 
        struct backlight_properties props;
        struct backlight_device *bl;
        struct gpio_backlight *gbl;
-       struct device_node *np = pdev->dev.of_node;
        int ret;
  
-       if (!pdata && !np) {
-               dev_err(&pdev->dev,
-                       "failed to find platform data or device tree node.\n");
-               return -ENODEV;
-       }
- 
        gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
        if (gbl == NULL)
                return -ENOMEM;
  
        gbl->dev = &pdev->dev;
  
-       if (np) {
+       if (pdev->dev.fwnode) {
                ret = gpio_backlight_probe_dt(pdev, gbl);
                if (ret)
                        return ret;
-       } else {
+       } else if (pdata) {
                /*
                 * Legacy platform data GPIO retrieveal. Do not expand
                 * the use of this code path, currently only used by one
@@@ -126,6 -122,10 +119,10 @@@
                gbl->gpiod = gpio_to_desc(pdata->gpio);
                if (!gbl->gpiod)
                        return -EINVAL;
+       } else {
+               dev_err(&pdev->dev,
+                       "failed to find platform data or device tree node.\n");
+               return -ENODEV;
        }
  
        memset(&props, 0, sizeof(props));
@@@ -146,19 -146,17 +143,17 @@@
        return 0;
  }
  
- #ifdef CONFIG_OF
  static struct of_device_id gpio_backlight_of_match[] = {
        { .compatible = "gpio-backlight" },
        { /* sentinel */ }
  };
  
  MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
- #endif
  
  static struct platform_driver gpio_backlight_driver = {
        .driver         = {
                .name           = "gpio-backlight",
-               .of_match_table = of_match_ptr(gpio_backlight_of_match),
+               .of_match_table = gpio_backlight_of_match,
        },
        .probe          = gpio_backlight_probe,
  };

diff --combined drivers/video/backlight/pwm_bl.c
index 20d379ac8440cbbe268cdca01d875ac56f468d7c,abfd1bca2c11f9f1f92eb17f75b379dcf94a3dbc..2201b8c786419d4df61726876895f97e5780fac5
--- 1/drivers/video/backlight/pwm_bl.c
--- 2/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@@ -1,8 -1,6 +1,6 @@@
 -// SPDX-License-Identifier: GPL-2.0
 +// SPDX-License-Identifier: GPL-2.0-only
  /*
-  * linux/drivers/video/backlight/pwm_bl.c
-  *
-  * simple PWM based backlight control, board code has to setup
+  * Simple PWM based backlight control, board code has to setup
   * 1) pin configuration so PWM waveforms can output
   * 2) platform_data being correctly configured
   */
@@@ -191,29 -189,17 +189,17 @@@ int pwm_backlight_brightness_default(st
                                     struct platform_pwm_backlight_data *data,
                                     unsigned int period)
  {
-       unsigned int counter = 0;
-       unsigned int i, n;
+       unsigned int i;
        u64 retval;
  
        /*
-        * Count the number of bits needed to represent the period number. The
-        * number of bits is used to calculate the number of levels used for the
-        * brightness-levels table, the purpose of this calculation is have a
-        * pre-computed table with enough levels to get linear brightness
-        * perception. The period is divided by the number of bits so for a
-        * 8-bit PWM we have 255 / 8 = 32 brightness levels or for a 16-bit PWM
-        * we have 65535 / 16 = 4096 brightness levels.
-        *
-        * Note that this method is based on empirical testing on different
-        * devices with PWM of 8 and 16 bits of resolution.
+        * Once we have 4096 levels there's little point going much higher...
+        * neither interactive sliders nor animation benefits from having
+        * more values in the table.
         */
-       n = period;
-       while (n) {
-               counter += n % 2;
-               n >>= 1;
-       }
+       data->max_brightness =
+               min((int)DIV_ROUND_UP(period, fls(period)), 4096);
  
-       data->max_brightness = DIV_ROUND_UP(period, counter);
        data->levels = devm_kcalloc(dev, data->max_brightness,
                                    sizeof(*data->levels), GFP_KERNEL);
        if (!data->levels)
@@@ -705,5 -691,5 +691,5 @@@ static struct platform_driver pwm_backl
  module_platform_driver(pwm_backlight_driver);
  
  MODULE_DESCRIPTION("PWM based Backlight Driver");
- MODULE_LICENSE("GPL");
+ MODULE_LICENSE("GPL v2");
  MODULE_ALIAS("platform:pwm-backlight");