linux-kernel - Re: [PATCH 3/3] arm64: boot: dts: ti: k3-am62l3-evm: enable WKUP UART wakeup from LPM

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Message-ID: <c5954858-7d62-4b57-801d-8a6fe9cccefc@ti.com>
Date: Tue, 6 Jan 2026 11:10:50 -0600
From: Kendall Willis <k-willis@...com>
To: Nishanth Menon <nm@...com>
CC: Vignesh Raghavendra <vigneshr@...com>, Tero Kristo <kristo@...nel.org>,
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Dhruva Gole <d-gole@...com>, "Bryan
 Brattlof" <bb@...com>, <vishalm@...com>, <sebin.francis@...com>,
	<msp@...libre.com>, <khilman@...libre.com>, <a-kaur@...com>,
	<s-kochidanadu@...com>, <linux-arm-kernel@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] arm64: boot: dts: ti: k3-am62l3-evm: enable WKUP UART
 wakeup from LPM

On 1/6/26 05:56, Nishanth Menon wrote:
> On 16:10-20260105, Kendall Willis wrote:
>> On 1/5/26 07:55, Nishanth Menon wrote:
>>> On 20:51-20251230, Kendall Willis wrote:
>>>> Change the status of the wkup_uart0_interconnect node to enabled. The
>>>> target-module node sets the UART SYSC and SYSS registers to allow wakeup
>>>> from WKUP UART in DeepSleep low power mode.
>>>>
>>>> Signed-off-by: Kendall Willis <k-willis@...com>
>>>> ---
>>>>    arch/arm64/boot/dts/ti/k3-am62l3-evm.dts | 4 ++++
>>>>    1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/ti/k3-am62l3-evm.dts b/arch/arm64/boot/dts/ti/k3-am62l3-evm.dts
>>>> index cae04cce337366b50928d39b0c888550b14e43d3..02b1a1c76b2ee05d49cd69d199a6aacdb1973fa0 100644
>>>> --- a/arch/arm64/boot/dts/ti/k3-am62l3-evm.dts
>>>> +++ b/arch/arm64/boot/dts/ti/k3-am62l3-evm.dts
>>>> @@ -359,3 +359,7 @@ &usb1 {
>>>>    	pinctrl-names = "default";
>>>>    	pinctrl-0 = <&usb1_default_pins>;
>>>>    };
>>>> +
>>>> +&wkup_uart0_interconnect {
>>>> +	status = "okay";
>>>> +};
>>>
>>> don't we need to set status okay and provide pinmux for wkup_uart?
>>>
>>
>> No, only the interconnect target node needs to be enabled because it manages
>> the SYSC register. The SYSC register configures the WKUP_UART to be able to
>> wakeup the SoC from system suspend. This allows the WKUP_UART to be wakeup
>> capable even if it is reserved by firmware.
>>
> 
> If wkup_uart is controlled by firmware, it should be managed by
> firmware. $subject claims that wkup_uart is being enabled, but it is
> not.
> 
> 

Okay, I will change the $subject to reflect the patch better in v2.

Best,
Kendall