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: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index bdfcc0a71db14c2f917ef31d660845a63430bef4..678b270631983a47718d5d8d78f395e9d639ec83 100644 (file)
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -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;