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

From: Aradhya Bhatia <aradhya.bhatia@linux.dev>
To: Vicente Bergas <vicencb@gmail.com>
Cc: Laurent.pinchart@ideasonboard.com, airlied@gmail.com,
	alexander.sverdlin@siemens.com, andrzej.hajda@intel.com,
	devarsht@ti.com, dri-devel <dri-devel@lists.freedesktop.org>,
	jernej.skrabec@gmail.com, "Jonas Karlman" <jonas@kwiboo.se>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	lumag@kernel.org, maarten.lankhorst@linux.intel.com,
	mripard@kernel.org, neil.armstrong@linaro.org, nm@ti.com,
	rfoss@kernel.org, simona@ffwll.ch,
	tomi.valkeinen@ideasonboard.com, tzimmermann@suse.de,
	vigneshr@ti.com,
	"Dmitry Baryshkov" <dmitry.baryshkov@oss.qualcomm.com>,
	"Douglas Anderson" <dianders@chromium.org>,
	"Damon Ding" <damon.ding@rock-chips.com>,
	"Sandy Huang" <hjc@rock-chips.com>,
	"Heiko Stübner" <heiko@sntech.de>,
	"Andy Yan" <andy.yan@rock-chips.com>,
	"Linux Rockchip Support List"
	<linux-rockchip@lists.infradead.org>,
	"Devarsh Thakkar" <devarsht@ti.com>
Subject: Re: [PATCH v13 3/4] drm/atomic-helper: Re-order bridge chain pre-enable and post-disable
Date: Mon, 6 Oct 2025 16:30:19 +0100	[thread overview]
Message-ID: <ff21cbd1-dc77-43ae-85a8-dc6a56a1cefa@linux.dev> (raw)
In-Reply-To: <bea50d14-2311-46ad-bb30-9d60a4c5e3a2@linux.dev>

+rockchip maintainers

Hi Vicente, all,

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

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