linux-kernel - [PATCH] pwm: rz-mtu3: Share parent device node to MTU3 PWM

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Message-ID: <20251009162445.701589-1-martyn.welch@collabora.com>
Date: Thu,  9 Oct 2025 17:24:44 +0100
From: Martyn Welch <martyn.welch@...labora.com>
To: Uwe Kleine-König <ukleinek@...nel.org>
Cc: kernel@...labora.com,
	Martyn Welch <martyn.welch@...labora.com>,
	Sebastian Reichel <sebastian.reichel@...labora.com>,
	linux-pwm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] pwm: rz-mtu3: Share parent device node to MTU3 PWM

The PWM currently functions, however if we try to utilise the pwn in a
device tree, for example as a pwm-backlight:

        lcd_bl: backlight {
                compatible = "pwm-backlight";
                pwms = <&mtu3 3 833333>;
		...

This fails:

[   15.603948] platform backlight: deferred probe pending: pwm-backlight: unable to request PWM

The PWM driver forms part of the Renesas Multi-Function Timer Pulse Unit
3. The PWM does not have a DT node of it's own. Share the DT node of the
parent MFD device, so that the PWM channels can be referenced via phandles.

Co-developed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
Signed-off-by: Martyn Welch <martyn.welch@...labora.com>
---
 drivers/pwm/pwm-rz-mtu3.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pwm/pwm-rz-mtu3.c b/drivers/pwm/pwm-rz-mtu3.c
index ab39bd37edafc..5825875fa0128 100644
--- a/drivers/pwm/pwm-rz-mtu3.c
+++ b/drivers/pwm/pwm-rz-mtu3.c
@@ -523,6 +523,12 @@ static int rz_mtu3_pwm_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
+	/*
+	 * There is only one DT node, get it from the parent MFD device, so
+	 * that the PWM channels can be referenced via phandles
+	 */
+	dev->of_node = dev->parent->of_node;
+
 	chip->ops = &rz_mtu3_pwm_ops;
 	ret = devm_pwmchip_add(&pdev->dev, chip);
 	if (ret)
-- 
2.51.0