Using led_set_brightness_sync() only works for LEDs which are connected
via some kind of external bus like I²C or SPI. But it doesn't work for
the simple use case of directly connected LEDs via GPIOs.
Because this function only honors the led_classdev::brightness_set_blocking
callback. But the LED-GPIO driver registers the
led_classdev::brightness_set member if the GPIO can be modified directly
and thus, TTY triggers fail silently with -ENOTSUPP.
With the previously used led_set_brightness() it works for both use cases.
This function first checks for the simple case where the GPIO can be changed
without additional overhead, and if it fails, does the modification via a
workqueue.
Signed-off-by: Juergen Borleis <[email protected]>
---
drivers/leds/trigger/ledtrig-tty.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
index f62db7e..af61281 100644
--- a/drivers/leds/trigger/ledtrig-tty.c
+++ b/drivers/leds/trigger/ledtrig-tty.c
@@ -122,12 +122,12 @@ static void ledtrig_tty_work(struct work_struct *work)
if (icount.rx != trigger_data->rx ||
icount.tx != trigger_data->tx) {
- led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
+ led_set_brightness(trigger_data->led_cdev, LED_ON);
trigger_data->rx = icount.rx;
trigger_data->tx = icount.tx;
} else {
- led_set_brightness_sync(trigger_data->led_cdev, LED_OFF);
+ led_set_brightness(trigger_data->led_cdev, LED_OFF);
}
out:
--
2.20.1
On Mon 2021-05-03 11:25:42, Juergen Borleis wrote:
> Using led_set_brightness_sync() only works for LEDs which are connected
> via some kind of external bus like I?C or SPI. But it doesn't work for
> the simple use case of directly connected LEDs via GPIOs.
Really? I'd need to check.
> Because this function only honors the led_classdev::brightness_set_blocking
> callback. But the LED-GPIO driver registers the
> led_classdev::brightness_set member if the GPIO can be modified directly
> and thus, TTY triggers fail silently with -ENOTSUPP.
>
> With the previously used led_set_brightness() it works for both use cases.
> This function first checks for the simple case where the GPIO can be changed
> without additional overhead, and if it fails, does the modification via a
> workqueue.
Yeah, but that is not what we want. We are already running in the
workqueue.
We really should have a API that can be called from process context,
and just simply sets the brightness.
Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek
Hello J?rgen,
On Mon, May 03, 2021 at 11:25:42AM +0200, Juergen Borleis wrote:
> Using led_set_brightness_sync() only works for LEDs which are connected
> via some kind of external bus like I?C or SPI. But it doesn't work for
> the simple use case of directly connected LEDs via GPIOs.
> Because this function only honors the led_classdev::brightness_set_blocking
> callback. But the LED-GPIO driver registers the
> led_classdev::brightness_set member if the GPIO can be modified directly
> and thus, TTY triggers fail silently with -ENOTSUPP.
>
> With the previously used led_set_brightness() it works for both use cases.
> This function first checks for the simple case where the GPIO can be changed
> without additional overhead, and if it fails, does the modification via a
> workqueue.
>
> Signed-off-by: Juergen Borleis <[email protected]>
> ---
> drivers/leds/trigger/ledtrig-tty.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
> index f62db7e..af61281 100644
> --- a/drivers/leds/trigger/ledtrig-tty.c
> +++ b/drivers/leds/trigger/ledtrig-tty.c
> @@ -122,12 +122,12 @@ static void ledtrig_tty_work(struct work_struct *work)
>
> if (icount.rx != trigger_data->rx ||
> icount.tx != trigger_data->tx) {
> - led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
> + led_set_brightness(trigger_data->led_cdev, LED_ON);
>
> trigger_data->rx = icount.rx;
> trigger_data->tx = icount.tx;
> } else {
> - led_set_brightness_sync(trigger_data->led_cdev, LED_OFF);
> + led_set_brightness(trigger_data->led_cdev, LED_OFF);
> }
This problem still exists, right?
I think the right thing here is to call led_set_brightness_nosleep()
however.
Having said that, I think there are too many variants of
led_set_brightness which makes it difficult to pick the right one.
(I'm aware of
- led_set_brightness_nosleep
- led_set_brightness_nopm
- led_set_brightness_sync
- led_set_brightness
and there are a few more static variants in led-core.c
(__led_set_brightness, __led_set_brightness_blocking,
set_brightness_delayed).)
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |
On Mon, 09 Jan 2023, Uwe Kleine-König wrote:
> Hello Jürgen,
>
> On Mon, May 03, 2021 at 11:25:42AM +0200, Juergen Borleis wrote:
> > Using led_set_brightness_sync() only works for LEDs which are connected
> > via some kind of external bus like I²C or SPI. But it doesn't work for
> > the simple use case of directly connected LEDs via GPIOs.
> > Because this function only honors the led_classdev::brightness_set_blocking
> > callback. But the LED-GPIO driver registers the
> > led_classdev::brightness_set member if the GPIO can be modified directly
> > and thus, TTY triggers fail silently with -ENOTSUPP.
> >
> > With the previously used led_set_brightness() it works for both use cases.
> > This function first checks for the simple case where the GPIO can be changed
> > without additional overhead, and if it fails, does the modification via a
> > workqueue.
> >
> > Signed-off-by: Juergen Borleis <[email protected]>
> > ---
> > drivers/leds/trigger/ledtrig-tty.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
> > index f62db7e..af61281 100644
> > --- a/drivers/leds/trigger/ledtrig-tty.c
> > +++ b/drivers/leds/trigger/ledtrig-tty.c
> > @@ -122,12 +122,12 @@ static void ledtrig_tty_work(struct work_struct *work)
> >
> > if (icount.rx != trigger_data->rx ||
> > icount.tx != trigger_data->tx) {
> > - led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
> > + led_set_brightness(trigger_data->led_cdev, LED_ON);
> >
> > trigger_data->rx = icount.rx;
> > trigger_data->tx = icount.tx;
> > } else {
> > - led_set_brightness_sync(trigger_data->led_cdev, LED_OFF);
> > + led_set_brightness(trigger_data->led_cdev, LED_OFF);
> > }
>
> This problem still exists, right?
>
> I think the right thing here is to call led_set_brightness_nosleep()
> however.
>
> Having said that, I think there are too many variants of
> led_set_brightness which makes it difficult to pick the right one.
>
> (I'm aware of
> - led_set_brightness_nosleep
> - led_set_brightness_nopm
> - led_set_brightness_sync
> - led_set_brightness
>
> and there are a few more static variants in led-core.c
> (__led_set_brightness, __led_set_brightness_blocking,
> set_brightness_delayed).)
This patch (and this response) was never sent to me.
Not a great deal I can do if I'm not aware of it.
--
Lee Jones [李琼斯]
On Fri, 23 Feb 2024, Lee Jones wrote:
> On Mon, 09 Jan 2023, Uwe Kleine-König wrote:
>
> > Hello Jürgen,
> >
> > On Mon, May 03, 2021 at 11:25:42AM +0200, Juergen Borleis wrote:
> > > Using led_set_brightness_sync() only works for LEDs which are connected
> > > via some kind of external bus like I²C or SPI. But it doesn't work for
> > > the simple use case of directly connected LEDs via GPIOs.
> > > Because this function only honors the led_classdev::brightness_set_blocking
> > > callback. But the LED-GPIO driver registers the
> > > led_classdev::brightness_set member if the GPIO can be modified directly
> > > and thus, TTY triggers fail silently with -ENOTSUPP.
> > >
> > > With the previously used led_set_brightness() it works for both use cases.
> > > This function first checks for the simple case where the GPIO can be changed
> > > without additional overhead, and if it fails, does the modification via a
> > > workqueue.
> > >
> > > Signed-off-by: Juergen Borleis <[email protected]>
> > > ---
> > > drivers/leds/trigger/ledtrig-tty.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
> > > index f62db7e..af61281 100644
> > > --- a/drivers/leds/trigger/ledtrig-tty.c
> > > +++ b/drivers/leds/trigger/ledtrig-tty.c
> > > @@ -122,12 +122,12 @@ static void ledtrig_tty_work(struct work_struct *work)
> > >
> > > if (icount.rx != trigger_data->rx ||
> > > icount.tx != trigger_data->tx) {
> > > - led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
> > > + led_set_brightness(trigger_data->led_cdev, LED_ON);
> > >
> > > trigger_data->rx = icount.rx;
> > > trigger_data->tx = icount.tx;
> > > } else {
> > > - led_set_brightness_sync(trigger_data->led_cdev, LED_OFF);
> > > + led_set_brightness(trigger_data->led_cdev, LED_OFF);
> > > }
> >
> > This problem still exists, right?
> >
> > I think the right thing here is to call led_set_brightness_nosleep()
> > however.
> >
> > Having said that, I think there are too many variants of
> > led_set_brightness which makes it difficult to pick the right one.
> >
> > (I'm aware of
> > - led_set_brightness_nosleep
> > - led_set_brightness_nopm
> > - led_set_brightness_sync
> > - led_set_brightness
> >
> > and there are a few more static variants in led-core.c
> > (__led_set_brightness, __led_set_brightness_blocking,
> > set_brightness_delayed).)
>
> This patch (and this response) was never sent to me.
>
> Not a great deal I can do if I'm not aware of it.
Starting to think I've gone too far back in the LEDs ML's history? =;-)
--
Lee Jones [李琼斯]