Hi,
On Tue, Apr 9, 2019 at 2:07 AM Robert Foss <robert.foss@xxxxxxxxxxxxx> wrote:
>
> Hey Fabio,
>
> On 4/8/19 10:37 PM, Fabio Estevam wrote:
> > Hi Robert,
> >
> > [Adding Gary]
Adding Troy, I'm no longer a full-time employee at Boundary Devices.
> > On Mon, Apr 8, 2019 at 2:54 PM Robert Foss <robert.foss@xxxxxxxxxxxxx> wrote:
> >>
> >> If a LVDS device is not connected, having the LVDS channels
> >> enabled will prevent imx-ldb from probing correctly even
> >> if other CRTCs are connected.
> >>
> >> Signed-off-by: Robert Foss <robert.foss@xxxxxxxxxxxxx>
> >> ---
> >> arch/arm/boot/dts/imx6qdl-nitrogen6_max.dtsi | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/arm/boot/dts/imx6qdl-nitrogen6_max.dtsi b/arch/arm/boot/dts/imx6qdl-nitrogen6_max.dtsi
> >> index 39200e5dc896..5b413cf4c250 100644
> >> --- a/arch/arm/boot/dts/imx6qdl-nitrogen6_max.dtsi
> >> +++ b/arch/arm/boot/dts/imx6qdl-nitrogen6_max.dtsi
> >> @@ -703,7 +703,7 @@
> >> status = "okay";
> >>
> >> lvds-channel@0 {
> >> - status = "okay";
> >> + status = "disabled";
> >>
> >> port@4 {
> >> reg = <4>;
> >> @@ -715,7 +715,7 @@
> >> };
> >>
> >> lvds-channel@1 {
> >> - status = "okay";
> >> + status = "disabled";
> >
> > I am not sure I understood what you are trying to fix.
>
> If CONFIG_DRM_IMX_LDB is enabled, LVDS DT channels are enabled
> and no LVDS-panels are connected the imx-ldb driver will
> fail to bind.
>
> This is a problem, since it will prevent other actually connected
> display output from being used, even if they bind properly.
>
> >
> > Could you please share some logs when imx-ldb fails to probe correctly?
>
>
> [ 2.119563] component_bind_all() trying to bind: ldb
> [ 2.124600] imx-drm display-subsystem: binding ldb (ops imx_ldb_ops)
> [ 2.146169] drm_of_find_panel_or_bridge() np->name=lvds-channel np->type=<NULL>
> [ 2.153709] drm_of_find_panel_or_bridge() no panel found for remote
> [ 2.160081] drm_of_find_panel_or_bridge() bridge needed
> [ 2.162043] drm_of_find_panel_or_bridge() bridge not found
> [ 2.165331] drm_of_find_panel_or_bridge() failed
> [ 2.170023] imx-drm display-subsystem: failed to bind ldb (ops imx_ldb_ops): -517
>
> This at the same time as HDMI binds properly:
>
> [ 4.458954] dwhdmi-imx 120000.hdmi: Detected HDMI TX controller v1.30a with
> HDCP (DWC HDMI 3D TX PHY)
> [ 4.469633] imx-drm display-subsystem: bound 120000.hdmi (ops dw_hdmi_imx_ops)
>
> Which in the end causes the IMX driver to not initialize properly
> and ignore the HDMI connection that bound properly.
> This in turn prevents us from having any graphical output while there
> is no LVDS panel connected.
Does this happen if the LVDS is disabled in cmdline? (adding "video=LVDS-1:d")
Note that a bootscript was written for mainline kernel that takes care
of display configuration [1].
Currently this bootscript disables all the displays that aren't used.
It was tested with HDMI, where LVDS and LCD display are disabled, and
it *used to* work.
If this doesn't work then there's most likely a regression somewhere.
Regards,
Gary
[1] https://github.com/boundarydevices/u-boot-imx6/blob/boundary-v2018.07/board/boundary/bootscripts/bootscript-mainline.txt#L90
