| Message ID | 20170717212811.25374-3-enric.balletbo@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 17/07/17 22:28, Enric Balletbo i Serra wrote: > Some panels (i.e. N116BGE-L41), in their power sequence specifications, > request a delay between set the PWM signal and enable the backlight and > between clear the PWM signal and disable the backlight. Add support for > the new post-pwm-on-delay-us and pwm-off-delay-us proprieties to meet > the timings. > > Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> > --- > Changes since v2: > - Move the pwm/enable sequence to another patch (Thierry Reding) > Changes since v1: > - As suggested by Daniel Thompson > - Do not assume power-on delay and power-off delay will be the same > - Move the check of dt property to the parse dt function. > > drivers/video/backlight/pwm_bl.c | 17 +++++++++++++++++ > include/linux/pwm_backlight.h | 1 + > 2 files changed, 18 insertions(+) > > diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c > index 909a686..528155d 100644 > --- a/drivers/video/backlight/pwm_bl.c > +++ b/drivers/video/backlight/pwm_bl.c > @@ -10,6 +10,7 @@ > * published by the Free Software Foundation. > */ > > +#include <linux/delay.h> > #include <linux/gpio/consumer.h> > #include <linux/gpio.h> > #include <linux/module.h> > @@ -35,6 +36,7 @@ struct pwm_bl_data { > struct gpio_desc *enable_gpio; > unsigned int scale; > bool legacy; > + unsigned int pwm_delay[2]; Two named members would be better here (eliminating the "magic" 0 and 1). > int (*notify)(struct device *, > int brightness); > void (*notify_after)(struct device *, > @@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) > > pwm_enable(pb->pwm); > > + if (pb->pwm_delay[0]) > + usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); > + > if (pb->enable_gpio) > gpiod_set_value_cansleep(pb->enable_gpio, 1); > > @@ -70,6 +75,9 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb) > if (pb->enable_gpio) > gpiod_set_value_cansleep(pb->enable_gpio, 0); > > + if (pb->pwm_delay[1]) > + usleep_range(pb->pwm_delay[1], pb->pwm_delay[1] * 2); > + > pwm_config(pb->pwm, 0, pb->period); > pwm_disable(pb->pwm); > > @@ -175,6 +183,14 @@ static int pwm_backlight_parse_dt(struct device *dev, > data->max_brightness--; > } > > + /* > + * These values are optional and set as 0 by default, the out values > + * are modified only if a valid u32 value can be decoded. > + */ > + of_property_read_u32(node, "post-pwm-on-delay-us", > + &data->pwm_delay[0]); > + of_property_read_u32(node, "pwm-off-delay-us", &data->pwm_delay[1]); > + > data->enable_gpio = -EINVAL; > return 0; > } > @@ -273,6 +289,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) > pb->exit = data->exit; > pb->dev = &pdev->dev; > pb->enabled = false; > + memcpy(pb->pwm_delay, data->pwm_delay, sizeof(pb->pwm_delay)); > > pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable", > GPIOD_ASIS); > diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h > index efdd922..bf37131 100644 > --- a/include/linux/pwm_backlight.h > +++ b/include/linux/pwm_backlight.h > @@ -13,6 +13,7 @@ struct platform_pwm_backlight_data { > unsigned int lth_brightness; > unsigned int pwm_period_ns; > unsigned int *levels; > + unsigned int pwm_delay[2]; > /* TODO remove once all users are switched to gpiod_* API */ > int enable_gpio; > int (*init)(struct device *dev); >
Hi! > >--- a/drivers/video/backlight/pwm_bl.c > >+++ b/drivers/video/backlight/pwm_bl.c > >@@ -10,6 +10,7 @@ > > * published by the Free Software Foundation. > > */ > >+#include <linux/delay.h> > > #include <linux/gpio/consumer.h> > > #include <linux/gpio.h> > > #include <linux/module.h> > >@@ -35,6 +36,7 @@ struct pwm_bl_data { > > struct gpio_desc *enable_gpio; > > unsigned int scale; > > bool legacy; > >+ unsigned int pwm_delay[2]; > > Two named members would be better here (eliminating the "magic" 0 >and 1). My thought, too. > >@@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) > > pwm_enable(pb->pwm); > >+ if (pb->pwm_delay[0]) > >+ usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); Plus I'd just do the delay unconditionally :-). Best regards, Pavel
On 20/07/17 09:06, Pavel Machek wrote: > Hi! > >>> --- a/drivers/video/backlight/pwm_bl.c >>> +++ b/drivers/video/backlight/pwm_bl.c >>> @@ -10,6 +10,7 @@ >>> * published by the Free Software Foundation. >>> */ >>> +#include <linux/delay.h> >>> #include <linux/gpio/consumer.h> >>> #include <linux/gpio.h> >>> #include <linux/module.h> >>> @@ -35,6 +36,7 @@ struct pwm_bl_data { >>> struct gpio_desc *enable_gpio; >>> unsigned int scale; >>> bool legacy; >>> + unsigned int pwm_delay[2]; >> >> Two named members would be better here (eliminating the "magic" 0 >> and 1). > > My thought, too. > >>> @@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) >>> pwm_enable(pb->pwm); >>> + if (pb->pwm_delay[0]) >>> + usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); > > Plus I'd just do the delay unconditionally :-). ... does this still apply if this code is switched to msleep()? msleep() has no wait avoidance[1] and if lots of drivers are reckless about sleeping for 10ms it soon starts to show up in the boot time (especially optimized ones). Daniel. [1] As it happens I can't see that many early bail out paths in usleep_range() either.
On Thu 2017-07-20 11:37:17, Daniel Thompson wrote: > On 20/07/17 09:06, Pavel Machek wrote: > >Hi! > > > >>>--- a/drivers/video/backlight/pwm_bl.c > >>>+++ b/drivers/video/backlight/pwm_bl.c > >>>@@ -10,6 +10,7 @@ > >>> * published by the Free Software Foundation. > >>> */ > >>>+#include <linux/delay.h> > >>> #include <linux/gpio/consumer.h> > >>> #include <linux/gpio.h> > >>> #include <linux/module.h> > >>>@@ -35,6 +36,7 @@ struct pwm_bl_data { > >>> struct gpio_desc *enable_gpio; > >>> unsigned int scale; > >>> bool legacy; > >>>+ unsigned int pwm_delay[2]; > >> > >>Two named members would be better here (eliminating the "magic" 0 > >>and 1). > > > >My thought, too. > > > >>>@@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) > >>> pwm_enable(pb->pwm); > >>>+ if (pb->pwm_delay[0]) > >>>+ usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); > > > >Plus I'd just do the delay unconditionally :-). > > ... does this still apply if this code is switched to msleep()? > > msleep() has no wait avoidance[1] and if lots of drivers are reckless about > sleeping for 10ms it soon starts to show up in the boot time (especially > optimized ones). No, not for msleep. Best regards, Pavel
On Thu 2017-07-20 11:37:17, Daniel Thompson wrote: > On 20/07/17 09:06, Pavel Machek wrote: > >Hi! > > > >>>--- a/drivers/video/backlight/pwm_bl.c > >>>+++ b/drivers/video/backlight/pwm_bl.c > >>>@@ -10,6 +10,7 @@ > >>> * published by the Free Software Foundation. > >>> */ > >>>+#include <linux/delay.h> > >>> #include <linux/gpio/consumer.h> > >>> #include <linux/gpio.h> > >>> #include <linux/module.h> > >>>@@ -35,6 +36,7 @@ struct pwm_bl_data { > >>> struct gpio_desc *enable_gpio; > >>> unsigned int scale; > >>> bool legacy; > >>>+ unsigned int pwm_delay[2]; > >> > >>Two named members would be better here (eliminating the "magic" 0 > >>and 1). > > > >My thought, too. > > > >>>@@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) > >>> pwm_enable(pb->pwm); > >>>+ if (pb->pwm_delay[0]) > >>>+ usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); > > > >Plus I'd just do the delay unconditionally :-). > > ... does this still apply if this code is switched to msleep()? No. > msleep() has no wait avoidance[1] and if lots of drivers are reckless about > sleeping for 10ms it soon starts to show up in the boot time (especially > optimized ones). ... > [1] As it happens I can't see that many early bail out paths in > usleep_range() either. Well, in usleep_range(1,2) should be fast enough operation, and usleep_range(0,0) should be similar to usleep_range(1,2) at worst :-). Pavel
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 909a686..528155d 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -10,6 +10,7 @@ * published by the Free Software Foundation. */ +#include <linux/delay.h> #include <linux/gpio/consumer.h> #include <linux/gpio.h> #include <linux/module.h> @@ -35,6 +36,7 @@ struct pwm_bl_data { struct gpio_desc *enable_gpio; unsigned int scale; bool legacy; + unsigned int pwm_delay[2]; int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *, @@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) pwm_enable(pb->pwm); + if (pb->pwm_delay[0]) + usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); + if (pb->enable_gpio) gpiod_set_value_cansleep(pb->enable_gpio, 1); @@ -70,6 +75,9 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb) if (pb->enable_gpio) gpiod_set_value_cansleep(pb->enable_gpio, 0); + if (pb->pwm_delay[1]) + usleep_range(pb->pwm_delay[1], pb->pwm_delay[1] * 2); + pwm_config(pb->pwm, 0, pb->period); pwm_disable(pb->pwm); @@ -175,6 +183,14 @@ static int pwm_backlight_parse_dt(struct device *dev, data->max_brightness--; } + /* + * These values are optional and set as 0 by default, the out values + * are modified only if a valid u32 value can be decoded. + */ + of_property_read_u32(node, "post-pwm-on-delay-us", + &data->pwm_delay[0]); + of_property_read_u32(node, "pwm-off-delay-us", &data->pwm_delay[1]); + data->enable_gpio = -EINVAL; return 0; } @@ -273,6 +289,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->exit = data->exit; pb->dev = &pdev->dev; pb->enabled = false; + memcpy(pb->pwm_delay, data->pwm_delay, sizeof(pb->pwm_delay)); pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable", GPIOD_ASIS); diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h index efdd922..bf37131 100644 --- a/include/linux/pwm_backlight.h +++ b/include/linux/pwm_backlight.h @@ -13,6 +13,7 @@ struct platform_pwm_backlight_data { unsigned int lth_brightness; unsigned int pwm_period_ns; unsigned int *levels; + unsigned int pwm_delay[2]; /* TODO remove once all users are switched to gpiod_* API */ int enable_gpio; int (*init)(struct device *dev);
Some panels (i.e. N116BGE-L41), in their power sequence specifications, request a delay between set the PWM signal and enable the backlight and between clear the PWM signal and disable the backlight. Add support for the new post-pwm-on-delay-us and pwm-off-delay-us proprieties to meet the timings. Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> --- Changes since v2: - Move the pwm/enable sequence to another patch (Thierry Reding) Changes since v1: - As suggested by Daniel Thompson - Do not assume power-on delay and power-off delay will be the same - Move the check of dt property to the parse dt function. drivers/video/backlight/pwm_bl.c | 17 +++++++++++++++++ include/linux/pwm_backlight.h | 1 + 2 files changed, 18 insertions(+)