linux-kernel - Re: [PATCH 0/7] dts: amlogic: enable UART RX and TX pull up by default

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Message-ID: <04c47466-b1a3-4eb2-8f28-95faa29ff45f@linaro.org>
Date: Mon, 31 Mar 2025 08:42:04 +0200
From: neil.armstrong@...aro.org
To: Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 linux-amlogic@...ts.infradead.org
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, jbrunet@...libre.com, khilman@...libre.com,
 christianshewitt@...il.com
Subject: Re: [PATCH 0/7] dts: amlogic: enable UART RX and TX pull up by
 default

On 29/03/2025 19:58, Martin Blumenstingl wrote:
> On the LibreELEC forum there have been reports that Odroid-C2 does not
> boot when UART is left disconnected [0]. It turns out that this can be
> solved by enabling the SoCs pull-up resistor on the UART RX and TX
> pads [1].
> It's not clear whether that specific Odroid-C2 board has a broken
> resistor, the resistor is not populated (either by accident or on
> purpose) or if there's another reason.
> 
> Testing on an SM1 X96-Air shows that pull-ups being enabled on UART
> RX and TX is actually the default (either set in vendor u-boot or an
> actual hardware default).
> 
> This series enables the UART RX and TX pull up resistors in the
> default pin configuration on all supported SoCs.
> 
> Testing has been done on:
> - GXBB Odroid-C1 on u-boot by a user in the LibreELEC forums [2]
> - Meson8b Odroid-C1 on Linux (with vendor u-boot)
> - SM1 X96-Air on Linux (with vendor u-boot)
> 
> Please include this early so the various CI systems can test these
> patches.
> 
> 
> [0] https://forum.libreelec.tv/thread/28586-odroid-c2-gxbb-s905-and-le-11-06-or-12-does-not-boot/?postID=195481#post195481
> [1] https://forum.libreelec.tv/thread/28586-odroid-c2-gxbb-s905-and-le-11-06-or-12-does-not-boot/?postID=195667#post195667
> [2] https://forum.libreelec.tv/thread/28586-odroid-c2-gxbb-s905-and-le-11-06-or-12-does-not-boot/?postID=195674#post195674
> 
> 
> Martin Blumenstingl (7):
>    ARM: dts: amlogic: meson8: enable UART RX and TX pull up by default
>    ARM: dts: amlogic: meson8b: enable UART RX and TX pull up by default
>    arm64: dts: amlogic: gxbb: enable UART RX and TX pull up by default
>    arm64: dts: amlogic: gxl: enable UART RX and TX pull up by default
>    arm64: dts: amlogic: g12: enable UART RX and TX pull up by default
>    arm64: dts: amlogic: axg: enable UART RX and TX pull up by default
>    arm64: dts: amlogic: a1: enable UART RX and TX pull up by default
> 
>   arch/arm/boot/dts/amlogic/meson8.dtsi             |  4 ++--
>   arch/arm/boot/dts/amlogic/meson8b.dtsi            |  4 ++--
>   arch/arm64/boot/dts/amlogic/meson-a1.dtsi         |  1 +
>   arch/arm64/boot/dts/amlogic/meson-axg.dtsi        | 12 ++++++------
>   arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi | 10 +++++-----
>   arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi       | 10 +++++-----
>   arch/arm64/boot/dts/amlogic/meson-gxl.dtsi        | 12 ++++++------
>   7 files changed, 27 insertions(+), 26 deletions(-)
> 

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>

I'll apply them now so they can be tested on -next for this whole cycle.

Thanks,
Neil