Re: [PATCH RFC 0/2] arm64: tegra: Add NVIDIA Jetson Nano 2GB Developer Kit support

[Thierry Reding]

On Sun, Jun 08, 2025 at 11:25:53PM -0500, Aaron Kling wrote:
> On Sun, Jun 8, 2025 at 11:24 PM Aaron Kling via B4 Relay
> <devnull+webgeek1234.gmail.com@xxxxxxxxxx> wrote:
> >
> > Signed-off-by: Aaron Kling <webgeek1234@xxxxxxxxx>
> > ---
> > Aaron Kling (2):
> >       dt-bindings: arm: tegra: Document Jetson Nano Devkits
> >       arm64: tegra: Add NVIDIA Jetson Nano 2GB Developer Kit support
> >
> >  Documentation/devicetree/bindings/arm/tegra.yaml   |  5 +++
> >  arch/arm64/boot/dts/nvidia/Makefile                |  2 +
> >  arch/arm64/boot/dts/nvidia/tegra210-p3541-0000.dts | 43 ++++++++++++++++++++++
> >  3 files changed, 50 insertions(+)
> > ---
> > base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
> > change-id: 20250513-p3452-059708ca9993
> >
> > Best regards,
> > --
> > Aaron Kling <webgeek1234@xxxxxxxxx>
> 
> This is sent as an RFC, because it doesn't fully work. In my tests,
> this boots and everything I can see works, except for hdmi. The
> hotplug detect pin never changes, regardless of hdmi plug state. This
> works as expected on the downstream 4.9 kernel. Based on the
> downstream kernel dt for p3541, it's almost identical to p3540, and
> I've mirrored those differences in this series. Things like the hpd
> pin are the same. I'm failing to see why hpd would work on p3450, but
> not on p3541, when using the same boot stack. Does anyone know why
> this doesn't work?

My recollection is that the HPD pin essentially loops back the +5V pin,
so that would be my prime suspect. Other than that I suppose it could be
a pinmux issue where HPD is muxed as something else.

Thierry

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