From e636c8d336489bf3eed5878299e6cc045bbad077 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:17:29 +0000
Subject: [PATCH] debug lk
---
kernel/drivers/video/backlight/pwm_bl.c | 240 +++++++++++++++++++++++++++++++++++------------------------
1 files changed, 143 insertions(+), 97 deletions(-)
diff --git a/kernel/drivers/video/backlight/pwm_bl.c b/kernel/drivers/video/backlight/pwm_bl.c
index 155515e..c4323e9 100644
--- a/kernel/drivers/video/backlight/pwm_bl.c
+++ b/kernel/drivers/video/backlight/pwm_bl.c
@@ -1,18 +1,12 @@
+// 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
- *
- * 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/delay.h>
#include <linux/gpio/consumer.h>
-#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
@@ -25,10 +19,14 @@
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
+static bool bl_quiescent;
+module_param_named(quiescent, bl_quiescent, bool, 0600);
+MODULE_PARM_DESC(quiescent,
+ "pwm bl quiescent when reboot quiescent [default=false]");
+
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
- unsigned int period;
unsigned int lth_brightness;
unsigned int *levels;
bool enabled;
@@ -46,10 +44,12 @@
void (*exit)(struct device *);
};
-static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
+static void pwm_backlight_power_on(struct pwm_bl_data *pb)
{
+ struct pwm_state state;
int err;
+ pwm_get_state(pb->pwm, &state);
if (pb->enabled)
return;
@@ -57,7 +57,8 @@
if (err < 0)
dev_err(pb->dev, "failed to enable power supply\n");
- pwm_enable(pb->pwm);
+ state.enabled = true;
+ pwm_apply_state(pb->pwm, &state);
if (pb->post_pwm_on_delay)
msleep(pb->post_pwm_on_delay);
@@ -70,7 +71,10 @@
static void pwm_backlight_power_off(struct pwm_bl_data *pb)
{
- if (!pb->enabled)
+ struct pwm_state state;
+
+ pwm_get_state(pb->pwm, &state);
+ if (!pb->enabled && !state.enabled)
return;
if (pb->enable_gpio)
@@ -79,8 +83,9 @@
if (pb->pwm_off_delay)
msleep(pb->pwm_off_delay);
- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ state.enabled = false;
+ state.duty_cycle = 0;
+ pwm_apply_state(pb->pwm, &state);
regulator_disable(pb->power_supply);
pb->enabled = false;
@@ -89,14 +94,17 @@
static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
{
unsigned int lth = pb->lth_brightness;
+ struct pwm_state state;
u64 duty_cycle;
+
+ pwm_get_state(pb->pwm, &state);
if (pb->levels)
duty_cycle = pb->levels[brightness];
else
duty_cycle = brightness;
- duty_cycle *= pb->period - lth;
+ duty_cycle *= state.period - lth;
do_div(duty_cycle, pb->scale);
return duty_cycle + lth;
@@ -105,23 +113,20 @@
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = bl_get_data(bl);
- int brightness = bl->props.brightness;
- int duty_cycle;
-
- if (bl->props.power != FB_BLANK_UNBLANK ||
- bl->props.fb_blank != FB_BLANK_UNBLANK ||
- bl->props.state & BL_CORE_FBBLANK)
- brightness = 0;
+ int brightness = backlight_get_brightness(bl);
+ struct pwm_state state;
if (pb->notify)
brightness = pb->notify(pb->dev, brightness);
if (brightness > 0) {
- duty_cycle = compute_duty_cycle(pb, brightness);
- pwm_config(pb->pwm, duty_cycle, pb->period);
- pwm_backlight_power_on(pb, brightness);
- } else
+ pwm_get_state(pb->pwm, &state);
+ state.duty_cycle = compute_duty_cycle(pb, brightness);
+ pwm_apply_state(pb->pwm, &state);
+ pwm_backlight_power_on(pb);
+ } else {
pwm_backlight_power_off(pb);
+ }
if (pb->notify_after)
pb->notify_after(pb->dev, brightness);
@@ -143,30 +148,16 @@
};
#ifdef CONFIG_OF
-#define PWM_LUMINANCE_SCALE 10000 /* luminance scale */
-
-/* An integer based power function */
-static u64 int_pow(u64 base, int exp)
-{
- u64 result = 1;
-
- while (exp) {
- if (exp & 1)
- result *= base;
- exp >>= 1;
- base *= base;
- }
-
- return result;
-}
+#define PWM_LUMINANCE_SHIFT 16
+#define PWM_LUMINANCE_SCALE (1 << PWM_LUMINANCE_SHIFT) /* luminance scale */
/*
* CIE lightness to PWM conversion.
*
* The CIE 1931 lightness formula is what actually describes how we perceive
* light:
- * Y = (L* / 902.3) if L* ≤ 0.08856
- * Y = ((L* + 16) / 116)^3 if L* > 0.08856
+ * Y = (L* / 903.3) if L* ≤ 8
+ * Y = ((L* + 16) / 116)^3 if L* > 8
*
* Where Y is the luminance, the amount of light coming out of the screen, and
* is a number between 0.0 and 1.0; and L* is the lightness, how bright a human
@@ -175,16 +166,25 @@
* The following function does the fixed point maths needed to implement the
* above formula.
*/
-static u64 cie1931(unsigned int lightness, unsigned int scale)
+static u64 cie1931(unsigned int lightness)
{
u64 retval;
+ /*
+ * @lightness is given as a number between 0 and 1, expressed
+ * as a fixed-point number in scale
+ * PWM_LUMINANCE_SCALE. Convert to a percentage, still
+ * expressed as a fixed-point number, so the above formulas
+ * can be applied.
+ */
lightness *= 100;
- if (lightness <= (8 * scale)) {
- retval = DIV_ROUND_CLOSEST_ULL(lightness * 10, 9023);
+ if (lightness <= (8 * PWM_LUMINANCE_SCALE)) {
+ retval = DIV_ROUND_CLOSEST(lightness * 10, 9033);
} else {
- retval = int_pow((lightness + (16 * scale)) / 116, 3);
- retval = DIV_ROUND_CLOSEST_ULL(retval, (scale * scale));
+ retval = (lightness + (16 * PWM_LUMINANCE_SCALE)) / 116;
+ retval *= retval * retval;
+ retval += 1ULL << (2*PWM_LUMINANCE_SHIFT - 1);
+ retval >>= 2*PWM_LUMINANCE_SHIFT;
}
return retval;
@@ -218,8 +218,7 @@
/* Fill the table using the cie1931 algorithm */
for (i = 0; i < data->max_brightness; i++) {
retval = cie1931((i * PWM_LUMINANCE_SCALE) /
- data->max_brightness, PWM_LUMINANCE_SCALE) *
- period;
+ data->max_brightness) * period;
retval = DIV_ROUND_CLOSEST_ULL(retval, PWM_LUMINANCE_SCALE);
if (retval > UINT_MAX)
return -EINVAL;
@@ -257,8 +256,6 @@
of_property_read_u32(node, "post-pwm-on-delay-ms",
&data->post_pwm_on_delay);
of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
-
- data->enable_gpio = -EINVAL;
/*
* Determine the number of brightness levels, if this property is not
@@ -397,6 +394,31 @@
}
#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;
@@ -450,7 +472,6 @@
struct device_node *node = pdev->dev.of_node;
struct pwm_bl_data *pb;
struct pwm_state state;
- struct pwm_args pargs;
unsigned int i;
int ret;
@@ -492,22 +513,6 @@
goto err_alloc;
}
- /*
- * Compatibility fallback for drivers still using the integer GPIO
- * platform data. Must go away soon.
- */
- if (!pb->enable_gpio && gpio_is_valid(data->enable_gpio)) {
- ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
- GPIOF_OUT_INIT_HIGH, "enable");
- if (ret < 0) {
- dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
- data->enable_gpio, ret);
- goto err_alloc;
- }
-
- pb->enable_gpio = gpio_to_desc(data->enable_gpio);
- }
-
pb->power_supply = devm_regulator_get(&pdev->dev, "power");
if (IS_ERR(pb->power_supply)) {
ret = PTR_ERR(pb->power_supply);
@@ -530,7 +535,52 @@
dev_dbg(&pdev->dev, "got pwm for backlight\n");
- if (!data->levels) {
+ /* Sync up PWM state. */
+ pwm_init_state(pb->pwm, &state);
+
+ /*
+ * The DT case will set the pwm_period_ns field to 0 and store the
+ * period, parsed from the DT, in the PWM device. For the non-DT case,
+ * set the period from platform data if it has not already been set
+ * via the PWM lookup table.
+ */
+ if (!state.period && (data->pwm_period_ns > 0))
+ state.period = data->pwm_period_ns;
+
+ ret = pwm_apply_state(pb->pwm, &state);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
+ ret);
+ goto err_alloc;
+ }
+
+ memset(&props, 0, sizeof(struct backlight_properties));
+
+ if (data->levels) {
+ pb->levels = data->levels;
+
+ /*
+ * For the DT case, only when brightness levels is defined
+ * data->levels is filled. For the non-DT case, data->levels
+ * can come from platform data, however is not usual.
+ */
+ for (i = 0; i <= data->max_brightness; i++)
+ if (data->levels[i] > pb->scale)
+ pb->scale = data->levels[i];
+
+ 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
+ * not set, use the default brightness table. For the DT case,
+ * max_brightness is set to 0 when brightness levels is not
+ * specified. For the non-DT case, max_brightness is usually
+ * set to some value.
+ */
+
/* Get the PWM period (in nanoseconds) */
pwm_get_state(pb->pwm, &state);
@@ -541,31 +591,28 @@
"failed to setup default brightness table\n");
goto err_alloc;
}
- }
- for (i = 0; i <= data->max_brightness; i++) {
- if (data->levels[i] > pb->scale)
- pb->scale = data->levels[i];
+ for (i = 0; i <= data->max_brightness; i++) {
+ if (data->levels[i] > pb->scale)
+ pb->scale = data->levels[i];
- pb->levels = data->levels;
+ pb->levels = data->levels;
+ }
+
+ props.scale = BACKLIGHT_SCALE_NON_LINEAR;
+ } else {
+ /*
+ * That only happens for the non-DT case, where platform data
+ * sets the max_brightness value.
+ */
+ pb->scale = data->max_brightness;
}
pwm_adjust_config(pb->pwm);
- /*
- * The DT case will set the pwm_period_ns field to 0 and store the
- * period, parsed from the DT, in the PWM device. For the non-DT case,
- * set the period from platform data if it has not already been set
- * via the PWM lookup table.
- */
- pwm_get_args(pb->pwm, &pargs);
- pb->period = pargs.period;
- if (!pb->period && (data->pwm_period_ns > 0))
- pb->period = data->pwm_period_ns;
+ pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
+ pb->scale));
- pb->lth_brightness = data->lth_brightness * (pb->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,
@@ -585,7 +632,12 @@
data->dft_brightness = data->max_brightness;
}
- bl->props.brightness = data->dft_brightness;
+ /* set brightness 0, when boot quiescent */
+ if (bl_quiescent)
+ bl->props.brightness = 0;
+ else
+ bl->props.brightness = data->dft_brightness;
+
bl->props.power = pwm_backlight_initial_power_state(pb);
backlight_update_status(bl);
@@ -628,9 +680,6 @@
struct backlight_device *bl = dev_get_drvdata(dev);
struct pwm_bl_data *pb = bl_get_data(bl);
- if (mem_sleep_current == PM_SUSPEND_MEM_LITE)
- return 0;
-
if (pb->notify)
pb->notify(pb->dev, 0);
@@ -645,9 +694,6 @@
static int pwm_backlight_resume(struct device *dev)
{
struct backlight_device *bl = dev_get_drvdata(dev);
-
- if (mem_sleep_current == PM_SUSPEND_MEM_LITE)
- return 0;
backlight_update_status(bl);
@@ -678,5 +724,5 @@
module_platform_driver(pwm_backlight_driver);
MODULE_DESCRIPTION("PWM based Backlight Driver");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:pwm-backlight");
--
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