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Date: Thu, 28 Mar 2024 17:27:03 +0100
Message-Id: <D05IVTPYH35N.2CLDG6LSILRSN@matfyz.cz>
Subject: [REGRESSION] PWM vibrator does not probe with v6.9-rc1
To: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
From: "Karel Balej" <balejk@matfyz.cz>
Cc: <regressions@lists.linux.dev>, <linux-pwm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>

Uwe,

I am working on bringing the mainline Linux to my old smartphone. Most
of the changes are not yet in-tree.

The phone has a PWM vibrator for which the corresponding input driver
(pwm-vibrator) is used. The driver used for the PWM is pwm-pxa (or
pxa25x-pwm).

The DT nodes look like this

[...]
	pwm: pwm@1ac00 {
		compatible =3D "marvell,pxa250-pwm";
		reg =3D <0x1ac00 0x10>;
		#pwm-cells =3D <1>;
		clocks =3D <&apbc PXA1908_CLK_PWM3>;
	};
[...]
	vibrator {
		compatible =3D "pwm-vibrator";
		pwm-names =3D "enable";
		pwms =3D <&pwm 100000>;
		enable-gpios =3D <&gpio 20 GPIO_ACTIVE_HIGH>;
		pinctrl-names =3D "default";
		pinctrl-0 =3D <&vibrator_pins>;
	};
[...]

The vibrator worked fine with v6.8-rc6 but after I rebased to v6.9-rc1,
it no longer probes printing

	[  +0.000118] pwm-vibrator vibrator: failed to apply initial PWM state: -2=
2

to dmesg.

I have bisected the problem to 40ade0c2e794 ("pwm: Let the of_xlate
callbacks accept references without period").

Looking at the commit and adjacent history, I don't believe this problem
is caused by this still being an out-of-tree DT, nonetheless, if it
proves to be the case, then I apologize for false alarm.

Would you please take a look?

Thank you and kind regards,
K. B.

#regzbot introduced: 40ade0c2e794