pwm-backlight driver not being probed in u-boot

Cheo Fusi fusibrandon13 at gmail.com
Mon Jan 9 15:20:14 CET 2023


Hi everyone,

I've been trying to turn on my lcd backlight at the u-boot stage to no
avail. The device tree has a top level node whose compatible is
'pwm-backlight'. That driver never seems to get probed. The same problem is
described here
<https://stackoverflow.com/questions/62461096/pwm-backlight-driver-not-being-probed-in-u-boot>

I'm new to u-boot so please bear with me. From what I can gather from the
docs a device gets activated/probed when *uclass_get_device *and friends
are called. However I keep getting NULL, while
*uclass_id_count(UCLASS_PANEL_BACKLIGHT)
*correctly reports 1 device. A *dm_dump_all* at this stage shows the
backlight is probed. All these calls are made in *board_late_init.*

Does this have to do with the backlight being a top level device in the
devicetree ?? Or is the a wrong assumption I'm making ? Any help would be
greatly appreciated.

Brandon


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