linux-kernel - [PATCH] leds: trigger/tty: Use led_set_brightness() to support all use cases

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Message-Id: <20210503092542.14497-1-jbe@pengutronix.de>
Date:   Mon,  3 May 2021 11:25:42 +0200
From:   Juergen Borleis <jbe@...gutronix.de>
To:     linux-leds@...r.kernel.org, Pavel Machek <pavel@....cz>
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kernel@...gutronix.de
Subject: [PATCH] leds: trigger/tty: Use led_set_brightness() to support all use cases

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@...gutronix.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);
 	}

 out:
-- 
2.20.1