Re: [PATCH 3/3] drm/panel: himax-hx83121a: add backlight regulator support

[Icenowy Zheng <zhengxingda@iscas.ac.cn>]

在 2026-06-11四的 13:26 +0800，Pengyu Luo写道：
> On Tue, 09 Jun 2026 00:26:22 +0800, Icenowy Zheng
> <zhengxingda@iscas.ac.cn> wrote:
> > diff --git a/drivers/gpu/drm/panel/panel-himax-hx83121a.c
> > b/drivers/gpu/drm/panel/panel-himax-hx83121a.c
> > index 1a7e0125bced..e31e2fba0a78 100644
> > --- a/drivers/gpu/drm/panel/panel-himax-hx83121a.c
> > +++ b/drivers/gpu/drm/panel/panel-himax-hx83121a.c
> > @@ -195,7 +197,27 @@ static int himax_bl_update_status(struct
> > backlight_device *bl)
> > [ ... skip 18 lines ... ]
> > +		ret = regulator_enable(ctx->bl_supply);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ctx->backlight_enabled = true;
> > +
> 
> If you use a pin, (it is indeed a hwen pin as we know) you can
> simplify it like this,
> 
> bool bl_enable_now = !!brightness;
> 
> if (ctx->bl_enable != bl_enable_now) {
> 	gpiod_set_value(ctx->hwen_gpio, bl_enable_now);
> 	ctx->bl_enable = bl_enable_now;
> }
> 
> BTW, iirc, panel bias can be turned off too, although I don't think
> this will save too much power.

BTW during my test, it seems that DCS backlight 0 isn't turning off
backlight.

Thanks,
Icenowy

> 
> Best wishes,
> Pengyu