From 865cac14c2dac2fa5f16d1781ca2746b0d323796 Mon Sep 17 00:00:00 2001 From: Lucas Stach Date: Mon, 8 Jul 2019 14:41:29 +0200 Subject: backlight: rave-sp: Leave initial state and register with correct device This way the backlight can be referenced through its device node and enabling/disabling can be managed through the panel driver. Signed-off-by: Lucas Stach Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/rave-sp-backlight.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/video/backlight/rave-sp-backlight.c b/drivers/video/backlight/rave-sp-backlight.c index 462f14a1b19d..05b5f003a3d1 100644 --- a/drivers/video/backlight/rave-sp-backlight.c +++ b/drivers/video/backlight/rave-sp-backlight.c @@ -48,14 +48,20 @@ static int rave_sp_backlight_probe(struct platform_device *pdev) struct device *dev = &pdev->dev; struct backlight_device *bd; - bd = devm_backlight_device_register(dev, pdev->name, dev->parent, + bd = devm_backlight_device_register(dev, pdev->name, dev, dev_get_drvdata(dev->parent), &rave_sp_backlight_ops, &rave_sp_backlight_props); if (IS_ERR(bd)) return PTR_ERR(bd); - backlight_update_status(bd); + /* + * If there is a phandle pointing to the device node we can + * assume that another device will manage the status changes. + * If not we make sure the backlight is in a consistent state. + */ + if (!dev->of_node->phandle) + backlight_update_status(bd); return 0; } -- cgit v1.2.3 From 072e2c8192cfc6ae1de1a2aca02d4512b69bdeed Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Tue, 23 Jul 2019 22:34:00 +0300 Subject: backlight: lm3630a: Switch to use fwnode_property_count_uXX() Use use fwnode_property_count_uXX() directly, that makes code neater. Signed-off-by: Andy Shevchenko Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/lm3630a_bl.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c index b04b35d007a2..2d8e8192e4e2 100644 --- a/drivers/video/backlight/lm3630a_bl.c +++ b/drivers/video/backlight/lm3630a_bl.c @@ -377,8 +377,7 @@ static int lm3630a_parse_led_sources(struct fwnode_handle *node, u32 sources[LM3630A_NUM_SINKS]; int ret, num_sources, i; - num_sources = fwnode_property_read_u32_array(node, "led-sources", NULL, - 0); + num_sources = fwnode_property_count_u32(node, "led-sources"); if (num_sources < 0) return default_led_sources; else if (num_sources > ARRAY_SIZE(sources)) -- cgit v1.2.3 From 30f644fd6ec9a0a241adb91579aaca7404132d7b Mon Sep 17 00:00:00 2001 From: Christophe JAILLET Date: Wed, 24 Jul 2019 23:38:28 +0200 Subject: backlight: lms283gf05: Fix a typo in the description passed to 'devm_gpio_request_one()' The description passed to 'devm_gpio_request_one()' should be related to LMS283GF05, not LMS285GF05. Signed-off-by: Christophe JAILLET Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/lms283gf05.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/video/backlight/lms283gf05.c b/drivers/video/backlight/lms283gf05.c index 35bc012b22cc..0e45685bcc1c 100644 --- a/drivers/video/backlight/lms283gf05.c +++ b/drivers/video/backlight/lms283gf05.c @@ -158,7 +158,7 @@ static int lms283gf05_probe(struct spi_device *spi) ret = devm_gpio_request_one(&spi->dev, pdata->reset_gpio, GPIOF_DIR_OUT | (!pdata->reset_inverted ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW), - "LMS285GF05 RESET"); + "LMS283GF05 RESET"); if (ret) return ret; } -- cgit v1.2.3 From bcd69da98e36afccb4cb5fbdbd2b7bb78c07184d Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Tue, 13 Aug 2019 13:58:53 +0200 Subject: video: backlight: Drop default m for {LCD,BACKLIGHT_CLASS_DEVICE} When running "make oldconfig" on a .config where CONFIG_BACKLIGHT_LCD_SUPPORT is not set, two new config options ("Lowlevel LCD controls" and "Lowlevel Backlight controls") appear, both defaulting to "m". Drop the "default m", as options should default to disabled, and because several driver config options already select LCD_CLASS_DEVICE or BACKLIGHT_CLASS_DEVICE when needed. Fixes: 8c5dc8d9f19c7992 ("video: backlight: Remove useless BACKLIGHT_LCD_SUPPORT kernel symbol") Signed-off-by: Geert Uytterhoeven Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/Kconfig | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers') diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index 8b081d61773e..40676be2e46a 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -10,7 +10,6 @@ menu "Backlight & LCD device support" # config LCD_CLASS_DEVICE tristate "Lowlevel LCD controls" - default m help This framework adds support for low-level control of LCD. Some framebuffer devices connect to platform-specific LCD modules @@ -143,7 +142,6 @@ endif # LCD_CLASS_DEVICE # config BACKLIGHT_CLASS_DEVICE tristate "Lowlevel Backlight controls" - default m help This framework adds support for low-level control of the LCD backlight. This includes support for brightness and power. -- cgit v1.2.3 From 28a1d72a221ecdf8f63205d40cb654c81a2b2da7 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Tue, 20 Aug 2019 17:34:39 +0200 Subject: video: backlight: tosa_lcd: drop check because i2c_unregister_device() is NULL safe No need to check the argument of i2c_unregister_device() because the function itself does it. Signed-off-by: Wolfram Sang Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/tosa_lcd.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/video/backlight/tosa_lcd.c b/drivers/video/backlight/tosa_lcd.c index 65cb7578776f..29af8e27b6e5 100644 --- a/drivers/video/backlight/tosa_lcd.c +++ b/drivers/video/backlight/tosa_lcd.c @@ -222,8 +222,7 @@ static int tosa_lcd_remove(struct spi_device *spi) { struct tosa_lcd_data *data = spi_get_drvdata(spi); - if (data->i2c) - i2c_unregister_device(data->i2c); + i2c_unregister_device(data->i2c); tosa_lcd_tg_off(data); -- cgit v1.2.3 From ec665b756e6f79c60078b00dbdabea3aa8a4b787 Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Wed, 31 Jul 2019 11:40:18 +0300 Subject: backlight: gpio-backlight: Correct initial power state handling The default-on property - or the def_value via legacy pdata) should be handled as: if it is 1, the backlight must be enabled (kept enabled) if it is 0, the backlight must be disabled (kept disabled) This only works for the case when default-on is set. If it is not set then the brightness of the backlight is set to 0. Now if the backlight is enabled by external driver (graphics) the backlight will stay disabled since the brightness is configured as 0. The backlight will not turn on. In order to minimize screen flickering during device boot: The initial brightness should be set to 1. If booted in non DT mode or no phandle link to the backlight node: follow the def_value/default-on to select UNBLANK or POWERDOWN If in DT boot we have phandle link then leave the GPIO in a state which the bootloader left it and let the user of the backlight to configure it further. Signed-off-by: Peter Ujfalusi Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/gpio_backlight.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) (limited to 'drivers') diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c index e84f3087e29f..18e053e4716c 100644 --- a/drivers/video/backlight/gpio_backlight.c +++ b/drivers/video/backlight/gpio_backlight.c @@ -59,13 +59,11 @@ static int gpio_backlight_probe_dt(struct platform_device *pdev, struct gpio_backlight *gbl) { struct device *dev = &pdev->dev; - enum gpiod_flags flags; int ret; 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); + gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS); if (IS_ERR(gbl->gpiod)) { ret = PTR_ERR(gbl->gpiod); @@ -79,6 +77,22 @@ static int gpio_backlight_probe_dt(struct platform_device *pdev, return 0; } +static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl) +{ + struct device_node *node = gbl->dev->of_node; + + /* Not booted with device tree or no phandle link to the node */ + if (!node || !node->phandle) + return gbl->def_value ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN; + + /* if the enable GPIO is disabled, do not enable the backlight */ + if (gpiod_get_value_cansleep(gbl->gpiod) == 0) + return FB_BLANK_POWERDOWN; + + return FB_BLANK_UNBLANK; +} + + static int gpio_backlight_probe(struct platform_device *pdev) { struct gpio_backlight_platform_data *pdata = @@ -136,7 +150,9 @@ static int gpio_backlight_probe(struct platform_device *pdev) return PTR_ERR(bl); } - bl->props.brightness = gbl->def_value; + bl->props.power = gpio_backlight_initial_power_state(gbl); + bl->props.brightness = 1; + backlight_update_status(bl); platform_set_drvdata(pdev, bl); -- cgit v1.2.3 From d55c028f8b25bdaaba9ae08026052b5b44d031b0 Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Tue, 9 Jul 2019 12:00:05 -0700 Subject: backlight: Expose brightness curve type through sysfs Backlight brightness curves can have different shapes. The two main types are linear and non-linear curves. The human eye doesn't perceive linearly increasing/decreasing brightness as linear (see also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED linearly to human eye"), hence many backlights use non-linear (often logarithmic) brightness curves. The type of curve currently is opaque to userspace, so userspace often uses more or less reliable heuristics (like the number of brightness levels) to decide whether to treat a backlight device as linear or non-linear. Export the type of the brightness curve via the new sysfs attribute 'scale'. The value of the attribute can be 'linear', 'non-linear' or 'unknown'. For devices that don't provide information about the scale of their brightness curve the value of the 'scale' attribute is 'unknown'. Signed-off-by: Matthias Kaehlcke Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- Documentation/ABI/testing/sysfs-class-backlight | 26 +++++++++++++++++++++++++ MAINTAINERS | 1 + drivers/video/backlight/backlight.c | 19 ++++++++++++++++++ include/linux/backlight.h | 8 ++++++++ 4 files changed, 54 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight (limited to 'drivers') diff --git a/Documentation/ABI/testing/sysfs-class-backlight b/Documentation/ABI/testing/sysfs-class-backlight new file mode 100644 index 000000000000..3ab175a3f5cb --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-backlight @@ -0,0 +1,26 @@ +What: /sys/class/backlight//scale +Date: July 2019 +KernelVersion: 5.4 +Contact: Daniel Thompson +Description: + Description of the scale of the brightness curve. + + The human eye senses brightness approximately logarithmically, + hence linear changes in brightness are perceived as being + non-linear. To achieve a linear perception of brightness changes + controls like sliders need to apply a logarithmic mapping for + backlights with a linear brightness curve. + + Possible values of the attribute are: + + unknown + The scale of the brightness curve is unknown. + + linear + The brightness changes linearly with each step. Brightness + controls should apply a logarithmic mapping for a linear + perception. + + non-linear + The brightness changes non-linearly with each step. Brightness + controls should use a linear mapping for a linear perception. diff --git a/MAINTAINERS b/MAINTAINERS index 5d7bb3024e13..fe75bb96a317 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2907,6 +2907,7 @@ F: include/linux/backlight.h F: include/linux/pwm_backlight.h F: Documentation/devicetree/bindings/leds/backlight F: Documentation/ABI/stable/sysfs-class-backlight +F: Documentation/ABI/testing/sysfs-class-backlight BATMAN ADVANCED M: Marek Lindner diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 5dc07106a59e..cac3e35d7630 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -32,6 +32,12 @@ static const char *const backlight_types[] = { [BACKLIGHT_FIRMWARE] = "firmware", }; +static const char *const backlight_scale_types[] = { + [BACKLIGHT_SCALE_UNKNOWN] = "unknown", + [BACKLIGHT_SCALE_LINEAR] = "linear", + [BACKLIGHT_SCALE_NON_LINEAR] = "non-linear", +}; + #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \ defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)) /* This callback gets called when something important happens inside a @@ -246,6 +252,18 @@ static ssize_t actual_brightness_show(struct device *dev, } static DEVICE_ATTR_RO(actual_brightness); +static ssize_t scale_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct backlight_device *bd = to_backlight_device(dev); + + if (WARN_ON(bd->props.scale > BACKLIGHT_SCALE_NON_LINEAR)) + return sprintf(buf, "unknown\n"); + + return sprintf(buf, "%s\n", backlight_scale_types[bd->props.scale]); +} +static DEVICE_ATTR_RO(scale); + static struct class *backlight_class; #ifdef CONFIG_PM_SLEEP @@ -292,6 +310,7 @@ static struct attribute *bl_device_attrs[] = { &dev_attr_brightness.attr, &dev_attr_actual_brightness.attr, &dev_attr_max_brightness.attr, + &dev_attr_scale.attr, &dev_attr_type.attr, NULL, }; diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 0b5897446dca..c7d6b2e8c3b5 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -46,6 +46,12 @@ enum backlight_notification { BACKLIGHT_UNREGISTERED, }; +enum backlight_scale { + BACKLIGHT_SCALE_UNKNOWN = 0, + BACKLIGHT_SCALE_LINEAR, + BACKLIGHT_SCALE_NON_LINEAR, +}; + struct backlight_device; struct fb_info; @@ -80,6 +86,8 @@ struct backlight_properties { enum backlight_type type; /* Flags used to signal drivers of state changes */ unsigned int state; + /* Type of the brightness scale (linear, non-linear, ...) */ + enum backlight_scale scale; #define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */ #define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */ -- cgit v1.2.3 From 511a204638d7d750f859c332635d09f38273b4f0 Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Tue, 9 Jul 2019 12:00:06 -0700 Subject: backlight: pwm_bl: Set scale type for CIE 1931 curves For backlight curves calculated with the CIE 1931 algorithm set the brightness scale type to non-linear. This makes the scale type available to userspace via the 'scale' sysfs attribute. Signed-off-by: Matthias Kaehlcke Tested-by: Enric Balletbo i Serra Acked-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/pwm_bl.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 2201b8c78641..d6d2b6407d7e 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -536,6 +536,8 @@ static int pwm_backlight_probe(struct platform_device *pdev) goto err_alloc; } + memset(&props, 0, sizeof(struct backlight_properties)); + if (data->levels) { /* * For the DT case, only when brightness levels is defined @@ -574,6 +576,8 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->levels = data->levels; } + + props.scale = BACKLIGHT_SCALE_NON_LINEAR; } else { /* * That only happens for the non-DT case, where platform data @@ -584,7 +588,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->lth_brightness = data->lth_brightness * (state.period / pb->scale); - memset(&props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; props.max_brightness = data->max_brightness; bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb, -- cgit v1.2.3 From c0b64faf0fe6ca2574a00faed1ae833130db4e08 Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Tue, 9 Jul 2019 12:00:07 -0700 Subject: backlight: pwm_bl: Set scale type for brightness curves specified in the DT Check if a brightness curve specified in the device tree is linear or not and set the corresponding property accordingly. This makes the scale type available to userspace via the 'scale' sysfs attribute. To determine if a curve is linear it is compared to a interpolated linear curve between min and max brightness. The curve is considered linear if no value deviates more than +/-5% of ${brightness_range} from their interpolated value. Signed-off-by: Matthias Kaehlcke Acked-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'drivers') diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index d6d2b6407d7e..746eebc411df 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -387,6 +387,31 @@ int pwm_backlight_brightness_default(struct device *dev, } #endif +static bool pwm_backlight_is_linear(struct platform_pwm_backlight_data *data) +{ + unsigned int nlevels = data->max_brightness + 1; + unsigned int min_val = data->levels[0]; + unsigned int max_val = data->levels[nlevels - 1]; + /* + * Multiplying by 128 means that even in pathological cases such + * as (max_val - min_val) == nlevels the error at max_val is less + * than 1%. + */ + unsigned int slope = (128 * (max_val - min_val)) / nlevels; + unsigned int margin = (max_val - min_val) / 20; /* 5% */ + int i; + + for (i = 1; i < nlevels; i++) { + unsigned int linear_value = min_val + ((i * slope) / 128); + unsigned int delta = abs(linear_value - data->levels[i]); + + if (delta > margin) + return false; + } + + return true; +} + static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb) { struct device_node *node = pb->dev->of_node; @@ -550,6 +575,11 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->levels = data->levels; } + + if (pwm_backlight_is_linear(data)) + props.scale = BACKLIGHT_SCALE_LINEAR; + else + props.scale = BACKLIGHT_SCALE_NON_LINEAR; } else if (!data->max_brightness) { /* * If no brightness levels are provided and max_brightness is -- cgit v1.2.3