From: Neil Armstrong <neil.armstrong@linaro.org>
To: Shigeaki Asai <y-asai.0816@docomonet.jp>,
Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: amlogic: odroid-go-ultra: use the RK818 RTC as rtc0
Date: Mon, 19 Oct 2026 09:29:07 +0200 [thread overview]
Message-ID: <0b5c28f0-0a43-42b3-a07e-4ecf39b2380d@linaro.org> (raw)
In-Reply-To: <20261017110743.3555391-1-y-asai.0816@docomonet.jp>
Hi,
On 10/17/26 13:07, Shigeaki Asai wrote:
> The ODROID-GO Ultra has two PMICs with an RTC each, RK818 and RK817,
> and the SoC has the meson virtual RTC. Only vrtc has an alias, rtc0.
>
> An RTC without an alias takes the lowest free number, and the RK817
> RTC registers early, so it usually becomes rtc0, the RTC the system
> time is set from at boot. The RK817 RTC seems to run without a 32kHz
> crystal on this board: it ran about 1.5% fast while the board was on
> and 14-17% slow while it was off. The RK818 RTC keeps time well:
> with it as rtc0, the clock was off by less than a second after the
> board was off, with no charger connected, for 12 hours 40 minutes.
>
> Use the RK818 RTC as rtc0, and give the other two RTCs an alias as
> well, so that the numbering does not depend on probe order.
>
> Fixes: 62e73f000696 ("arm64: dts: amlogic: add initial Odroid Go Ultra DTS")
> Assisted-by: claude-opus-5-5
> Signed-off-by: Shigeaki Asai <y-asai.0816@docomonet.jp>
> ---
> arch/arm64/boot/dts/amlogic/meson-g12b-odroid-go-ultra.dts | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-go-ultra.dts b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-go-ultra.dts
> index 348baa4e6d84..86902f68d7d4 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-go-ultra.dts
> +++ b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-go-ultra.dts
> @@ -18,7 +18,9 @@ / {
>
> aliases {
> serial0 = &uart_AO;
> - rtc0 = &vrtc;
> + rtc0 = &rk818;
> + rtc1 = &vrtc;
> + rtc2 = &rk817;
The vrtc was used as rtc0 because it's the defaut wakeup rtc,
can the rk818 and rk817 wakeup the system when in system suspend ?
Neil
> };
>
> adc-joystick-left {
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next prev parent reply other threads:[~2026-10-19 7:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 11:07 Shigeaki Asai
2026-10-19 7:29 ` Neil Armstrong [this message]
2026-10-19 13:04 ` Asai, Shigeaki
-- strict thread matches above, loose matches on Subject: below --
2026-10-13 22:49 Shigeaki Asai
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