[Intel-gfx] Regarding the laptop with the BOE panel with ID 2270

[Aaron Ma]

Hi Lyude,

I have tested this BOE2270 panel which belong to ThinkPad P17, and metion it in
the issue #3158, even with your patch:
"drm/i915/dpcd_bl: Don't try vesa interface unless specified by VBT"

drm-tip with/without "i915.enable_dpcd_backlight=3", backlight always can work as expected.
log is attached.

Looks like both of PWM and AUX can work on 5.12-rc kernel, but not sure which commit
did it.

BR,
Aaron

On 3/25/21 4:58 AM, Lyude Paul wrote:
> Hey Aaron! A while ago you submitted some patches for a machine that appears to
> have needed the VESA backlight interface in order to control the panel backlight
> on it:
>
> https://patchwork.freedesktop.org/patch/394371/
>
> We're currently dealing with a different laptop where the machine advertises
> VESA backlight support, which we end up defaulting to after failing to probe for
> the Intel backlight interface, but this backlight interface appears to be
> broken:
>
> https://gitlab.freedesktop.org/drm/intel/-/issues/3158
>
> The fix I was hoping to do was to just not attempt probing for the VESA
> backlight interface, but if we did that then it's possible that the backlight
> controls for the machine you submitted your patch for would stop working out of
> the box. However, it occurred to me that we never tried the Intel backlight
> interface on your machine - and if it works there, then we'd likely be able to
> require the VBT to advertise VESA support before using it and fix the machine in
> the gitlab issue I've linked.
>
> Do you think you could test this for us? If you build the latest kernel from
> drm-tip, the easiest way should be to boot up with
> "i915.enable_dpcd_backlight=3" and just see if your backlight controls still
> work as expected.

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