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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Thierry Reding <thierry.reding@gmail.com>,
	Lee Jones <lee@kernel.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jingoo Han <jingoohan1@gmail.com>
Cc: linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-fbdev@vger.kernel.org, kernel@pengutronix.de
Subject: [PATCH 2/2] backlight: pwm_bl: Don't disable the PWM to disable the backlight
Date: Mon,  9 Jan 2023 21:47:58 +0100	[thread overview]
Message-ID: <20230109204758.610400-2-u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <20230109204758.610400-1-u.kleine-koenig@pengutronix.de>

Most but not all PWMs drive the PWM pin to its inactive state when
disabled. Rely on the lowlevel PWM implementation to implement
duty_cycle = 0 in an energy efficient way and don't disable the PWM.

This fixes backlight disabling e.g. on i.MX6 when an inverted PWM is
used.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/video/backlight/pwm_bl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 0509fecd5715..7bdc5d570a12 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -109,7 +109,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 		pwm_backlight_power_off(pb);
 
 		pwm_get_state(pb->pwm, &state);
-		state.enabled = false;
+		state.enabled = true;
 		state.duty_cycle = 0;
 		pwm_apply_state(pb->pwm, &state);
 	}
-- 
2.39.0


WARNING: multiple messages have this Message-ID (diff)
From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Thierry Reding <thierry.reding@gmail.com>,
	Lee Jones <lee@kernel.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jingoo Han <jingoohan1@gmail.com>
Cc: linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org,
	kernel@pengutronix.de, dri-devel@lists.freedesktop.org
Subject: [PATCH 2/2] backlight: pwm_bl: Don't disable the PWM to disable the backlight
Date: Mon,  9 Jan 2023 21:47:58 +0100	[thread overview]
Message-ID: <20230109204758.610400-2-u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <20230109204758.610400-1-u.kleine-koenig@pengutronix.de>

Most but not all PWMs drive the PWM pin to its inactive state when
disabled. Rely on the lowlevel PWM implementation to implement
duty_cycle = 0 in an energy efficient way and don't disable the PWM.

This fixes backlight disabling e.g. on i.MX6 when an inverted PWM is
used.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/video/backlight/pwm_bl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 0509fecd5715..7bdc5d570a12 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -109,7 +109,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 		pwm_backlight_power_off(pb);
 
 		pwm_get_state(pb->pwm, &state);
-		state.enabled = false;
+		state.enabled = true;
 		state.duty_cycle = 0;
 		pwm_apply_state(pb->pwm, &state);
 	}
-- 
2.39.0


  reply	other threads:[~2023-01-09 20:48 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-09 20:47 [PATCH 1/2] backlight: pwm_bl: configure pwm only once per backlight toggle Uwe Kleine-König
2023-01-09 20:47 ` Uwe Kleine-König
2023-01-09 20:47 ` Uwe Kleine-König [this message]
2023-01-09 20:47   ` [PATCH 2/2] backlight: pwm_bl: Don't disable the PWM to disable the backlight Uwe Kleine-König
2023-01-10 16:26   ` Daniel Thompson
2023-01-10 16:26     ` Daniel Thompson
2023-01-10 17:35     ` Uwe Kleine-König
2023-01-10 17:50       ` Daniel Thompson
2023-01-10 16:17 ` [PATCH 1/2] backlight: pwm_bl: configure pwm only once per backlight toggle Daniel Thompson
2023-01-10 16:17   ` Daniel Thompson
2023-01-10 17:17   ` Uwe Kleine-König

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