From: Lee Jones <lee@kernel.org>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Juergen Borleis <jbe@pengutronix.de>,
linux-leds@vger.kernel.org, Pavel Machek <pavel@ucw.cz>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, kernel@pengutronix.de
Subject: Re: [PATCH] leds: trigger/tty: Use led_set_brightness() to support all use cases
Date: Fri, 23 Feb 2024 14:24:42 +0000 [thread overview]
Message-ID: <20240223142442.GB1666215@google.com> (raw)
In-Reply-To: <20240223142218.GA1666215@google.com>
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 <jbe@pengutronix.de>
> > > ---
> > > 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]
prev parent reply other threads:[~2024-02-23 14:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-03 9:25 [PATCH] leds: trigger/tty: Use led_set_brightness() to support all use cases Juergen Borleis
2021-05-03 10:16 ` Pavel Machek
2023-01-09 8:43 ` Uwe Kleine-König
2024-02-23 14:22 ` Lee Jones
2024-02-23 14:24 ` Lee Jones [this message]
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