linux-kernel - Re: [PATCH v13 3/4] drm/atomic-helper: Re-order bridge chain pre-enable and post-disable

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Message-ID: <CAAMcf8Di8sc_XVZAnzQ9sUiUf-Ayvg2yjhx2dWmvvCnfF3pBRA@mail.gmail.com>
Date: Mon, 1 Dec 2025 20:34:37 +0100
From: Vicente Bergas <vicencb@...il.com>
To: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
Cc: Laurent.pinchart@...asonboard.com, airlied@...il.com, 
	alexander.sverdlin@...mens.com, andrzej.hajda@...el.com, 
	dri-devel <dri-devel@...ts.freedesktop.org>, jernej.skrabec@...il.com, 
	Jonas Karlman <jonas@...boo.se>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, lumag@...nel.org, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, 
	neil.armstrong@...aro.org, nm@...com, rfoss@...nel.org, simona@...ll.ch, 
	tomi.valkeinen@...asonboard.com, tzimmermann@...e.de, vigneshr@...com, 
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
	Douglas Anderson <dianders@...omium.org>, Damon Ding <damon.ding@...k-chips.com>, 
	Sandy Huang <hjc@...k-chips.com>, Heiko Stübner <heiko@...ech.de>, 
	Andy Yan <andy.yan@...k-chips.com>, 
	Linux Rockchip Support List <linux-rockchip@...ts.infradead.org>, Devarsh Thakkar <devarsht@...com>
Subject: Re: [PATCH v13 3/4] drm/atomic-helper: Re-order bridge chain
 pre-enable and post-disable

On Mon, Oct 6, 2025 at 5:30 PM Aradhya Bhatia <aradhya.bhatia@...ux.dev> wrote:
>
> +rockchip maintainers
>
> Hi Vicente, all,

Hi everybody,
please, can some expert on this platform take a look at this bug?

Regards,
  Vicente.

> I went through the drivers and the affected areas in the gru-kevin
> chromebook pipeline last week, but nothing has stood out.
>
>
> Pipeline:
>
> rockchip,display-subsystem / rk3399-vop (Big/Lite) (CRTC) ->
> rk3399-edp (Encoder) -> analogix_dp_core (Bridge) ->
> sharp,lq123p (edp-panel)
>
> I am unable to debug this further since I do not have the hardware.
>
> I could use some help, especially from folks who understand the hardware
> requirements better.
>
>
> On 11/09/25 09:01, Aradhya Bhatia wrote:
> > Hi Vicente,
> >
> > Thank you for the bisection and reporting the issue.
> >
> > On 10/09/25 16:17, Vicente Bergas wrote:
> >> Hi,
> >> this patch causes a regression. It has been reported in
> >> https://bugzilla.kernel.org/show_bug.cgi?id=220554
> >>
> >> It affects the gru/kevin platform (arm64,RK3399) with the Panfrost DRM driver.
> >
> > I believe the Panfrost DRM driver may only be for the GPU.
> >
> > Based on the dts files in arm64/rockchip/, this is the pipeline of the
> > gru-kevin setup that I understand.
> >
> >       rk3399-vop (Big/Lite) -> rk3399-edp -> sharp,lq123p (edp-panel)
> >
> > The setup seems to be using the drm/rockchip drivers for the display
> > controller and for the bridge.
> >
> >>
> >> When it boots in console mode, the blinking of the cursor keeps the display on.
> >> If it is turned off via /sys/class/graphics/fbcon/cursor_blink, then
> >> the display briefly shows each key press presented on screen for less
> >> than one second and then powers off.
> >>
> >> When starting the graphical mode (wayland), if there are no
> >> applications drawing on the screen, the only way to keep the display
> >> on is by continuously moving the mouse.
> >>
> >
> > Okay!
> >
> > I will have a look through the drivers. In the meanwhile, please do
> > report back if you find any other observations.
> >
> >
>
> --
> Regards
> Aradhya
>