Hi,

On Mon, Jul 31, 2023 at 11:33:22AM -0500, Chris Morgan wrote:

In my case a few different panel drivers disable the regulators in the
unprepare/disable routines.

And that's totally fine.

For at least the Rockchip DSI implementations for some reason the
panel gets unprepared more than once, which triggers an unbalanced
regulator disable.

"For some reason" being that DW-DSI apparently finds it ok to bypass any
kind of abstraction and randomly calling panel functions by itself:

https://elixir.bootlin.com/linux/v6.4.7/source/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c#L868

It looks like it's fixed it current drm-misc-next though.

Obviously though the correct course of action is to fix the reason why
the panel is disabled more than once, but that's at least the root
cause of this behavior on the few panels I've worked with.

Like I said we already have a commit on the way to fix that, so it
shouldn't be an issue anymore.

I stand by what I was saying earlier though, I think it's mostly
cargo-cult or drivers being very wrong. If anything, the DW-DSI stuff
made me even more convinced that we shouldn't even entertain that idea
:)

Maxime