[PATCH v3] backlight: pwm_bl: switch to using "atomic" PWM API
Enric Balletbo i Serra
enric.balletbo at collabora.com
Tue Aug 14 16:50:59 UTC 2018
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 at collabora.com>
---
Changes in v3:
- Get rid of duty_cycle variable from pwm_backlight_update_status.
- Get rid of pb->enabled and use only the status.enabled variable.
- Make power_on match power_off.
- Do not share status between ...update_status and ...power_on
Changes in v2:
- Do not force the PWM be off in the first call to pwm_apply_state.
- Delayed applying the state until we know what the period is.
- Removed pb->period as after the conversion is not needed.
drivers/video/backlight/pwm_bl.c | 81 +++++++++++++++++---------------
1 file changed, 42 insertions(+), 39 deletions(-)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index bdfcc0a71db1..678b27063198 100644
--- 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;
--
2.18.0
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