Commit e6bcca08 authored by Enric Balletbo i Serra's avatar Enric Balletbo i Serra Committed by Lee Jones
Browse files

backlight: pwm_bl: Switch to using "atomic" PWM API 



The "atomic" API allows us to configure PWM period and duty_cycle and
enable it in one call.

The patch also moves the pwm_init_state just before any use of the
pwm_state struct, this fixes a potential bug where pwm_get_state
can be called before pwm_init_state.

Signed-off-by: default avatarEnric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Tested-by: default avatarHeiko Stuebner <heiko@sntech.de>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 0b193400

drivers/video/backlight/pwm_bl.c

+42 −39
Original line number Diff line number Diff line
@@ -28,10 +28,8 @@ 
struct pwm_bl_data {

	struct pwm_device	*pwm;

	struct device		*dev;

	unsigned int		period;

	unsigned int		lth_brightness;

	unsigned int		*levels;

	bool			enabled;

	struct regulator	*power_supply;

	struct gpio_desc	*enable_gpio;

	unsigned int		scale;
@@ -46,31 +44,35 @@ struct pwm_bl_data { 
	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;



	if (pb->enabled)

	pwm_get_state(pb->pwm, &state);

	if (state.enabled)

		return;



	err = regulator_enable(pb->power_supply);

	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);



	if (pb->enable_gpio)

		gpiod_set_value_cansleep(pb->enable_gpio, 1);



	pb->enabled = true;

}



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 (!state.enabled)

		return;



	if (pb->enable_gpio)
@@ -79,24 +81,27 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb) 
	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;

}



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;
@@ -106,7 +111,7 @@ 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;

	struct pwm_state state;



	if (bl->props.power != FB_BLANK_UNBLANK ||

	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
@@ -117,9 +122,10 @@ static int pwm_backlight_update_status(struct backlight_device *bl) 
		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);

		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);
@@ -447,7 +453,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) 
	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;
@@ -478,7 +483,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) 
	pb->check_fb = data->check_fb;

	pb->exit = data->exit;

	pb->dev = &pdev->dev;

	pb->enabled = false;

	pb->post_pwm_on_delay = data->post_pwm_on_delay;

	pb->pwm_off_delay = data->pwm_off_delay;
@@ -539,10 +543,26 @@ static int pwm_backlight_probe(struct platform_device *pdev) 


	dev_dbg(&pdev->dev, "got pwm for backlight\n");



	if (!data->levels) {

		/* Get the PWM period (in nanoseconds) */

		pwm_get_state(pb->pwm, &state);

	/* 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;

	}



	if (!data->levels) {

		ret = pwm_backlight_brightness_default(&pdev->dev, data,

						       state.period);

		if (ret < 0) {
@@ -559,24 +579,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) 
		pb->levels = data->levels;

	}



	/*

	 * FIXME: pwm_apply_args() should be removed when switching to

	 * the atomic PWM API.

	 */

	pwm_apply_args(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 * (pb->period / pb->scale);

	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);



	memset(&props, 0, sizeof(struct backlight_properties));

	props.type = BACKLIGHT_RAW;

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