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Subjectpwm: sun4i: pwm-backlight not working since 5.6-rc1
Hi all,

I am working on adding an old A10 device to mainline and noticed an
issue when testing on 5.5.8 vs master.

Since 5.6-rc1, I can't control the brightness of my LCD backlight
anymore. The backlight stays on full brightness instead. I am
controlling the brightness value via sysfs for testing.

I am not sure if this is a general pwm-sun4i issue or if it is related
to the backlight. However I narrowed it down to one commit for
pwm-sun4i:

fa4d81784681a26bcf7d2a43c6ac5cf991ef28f5

If I use pwm-sun4i.c from 5b090b430d750961305030232314b6acdb0102aa on
master, the backlight works fine. Unfortunately, due to my lack of
kernel experience, I can't see how the commit above broke it.

Not sure if it helps, but the binding for the backlight is as follows:

backlight: backlight {
compatible = "pwm-backlight";
pwms = <&pwm 0 100000 PWM_POLARITY_INVERTED>;
power-supply = <&reg_vbat>;
enable-gpios = <&pio 7 7 GPIO_ACTIVE_HIGH>; /* PH7 */
brightness-levels = <0 30 40 50 60 70 80 90 100>;
default-brightness-level = <8>;
};

Please let me know if there is anything else which might be helpful to
know or anything I can test.

Regards,
Pascal

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