linux-kernel - Re: [PATCH] soc: apple: rtkit: Add function to poweroff

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Message-ID: <20260117173819.GA55832@robin.jannau.net>
Date: Sat, 17 Jan 2026 18:38:19 +0100
From: Janne Grunau <j@...nau.net>
To: Sven Peter <sven@...nel.org>
Cc: Neal Gompa <neal@...pa.dev>, asahi@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc: apple: rtkit: Add function to poweroff

On Sat, Jan 17, 2026 at 06:24:44PM +0100, Sven Peter wrote:
> Add a function to put a co-processor into the lowest possible power
> state from which recovery usually isn't possible without a full SoC
> reset. This is required for the USB4/Thunderbolt co-processors which
> can be restarted since the entire USB4 root complex can be completely
> reset independently of the rest of the SoC.
> 
> Signed-off-by: Sven Peter <sven@...nel.org>
> ---
>  drivers/soc/apple/rtkit.c       | 17 +++++++++++++++++
>  include/linux/soc/apple/rtkit.h |  7 +++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/soc/apple/rtkit.c b/drivers/soc/apple/rtkit.c
> index b8d4da147d23f7e99e76eea314e4d976cddbd1c6..381faaf74d5982163d2c44d1e2c6e0ddad07bd73 100644
> --- a/drivers/soc/apple/rtkit.c
> +++ b/drivers/soc/apple/rtkit.c
> @@ -851,6 +851,23 @@ int apple_rtkit_shutdown(struct apple_rtkit *rtk)
>  }
>  EXPORT_SYMBOL_GPL(apple_rtkit_shutdown);
>  
> +int apple_rtkit_poweroff(struct apple_rtkit *rtk)
> +{
> +	int ret;
> +
> +	ret = apple_rtkit_set_ap_power_state(rtk,
> +					     APPLE_RTKIT_PWR_STATE_OFF);
> +	if (ret)
> +		return ret;
> +
> +	ret = apple_rtkit_set_iop_power_state(rtk, APPLE_RTKIT_PWR_STATE_OFF);

inconsistent line wrapping. It's wrapped for AP power state which is 1
character shorter. I would wrap neither it only moves the statement 4
places to the left.

> +	if (ret)
> +		return ret;
> +
> +	return apple_rtkit_reinit(rtk);
> +}
> +EXPORT_SYMBOL_GPL(apple_rtkit_poweroff);
> +
>  int apple_rtkit_idle(struct apple_rtkit *rtk)
>  {
>  	int ret;
> diff --git a/include/linux/soc/apple/rtkit.h b/include/linux/soc/apple/rtkit.h
> index 736f530180179bd144cf85eb0f0bd93844d7188a..bda3c528b51553c13f7fe5685ab60f7fc675361b 100644
> --- a/include/linux/soc/apple/rtkit.h
> +++ b/include/linux/soc/apple/rtkit.h
> @@ -125,6 +125,13 @@ int apple_rtkit_wake(struct apple_rtkit *rtk);
>   */
>  int apple_rtkit_shutdown(struct apple_rtkit *rtk);
>  
> +/*
> + * Put the co-processor into the lowest power state. Note that it usually
> + * is not possible to recover from this state without a full SoC reset.
> + */
> +
> +int apple_rtkit_poweroff(struct apple_rtkit *rtk);
> +
>  /*
>   * Put the co-processor into idle mode
>   */
> 

Feel free to fix without sending a v2

Reviewed-by: Janne Grunau <j@...nau.net>

Janne