linux-kernel - Re: [PATCH v2 2/2] clocksource: Add Realtek systimer as tick broadcast driver

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Message-ID: <d8320e3c-17de-43e5-b3b8-b6eaf16e1b61@kernel.org>
Date: Fri, 14 Nov 2025 10:12:53 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Hao-Wen Ting <haowen.ting@...ltek.com>, daniel.lezcano@...aro.org,
 tglx@...utronix.de
Cc: jinn.cheng@...ltek.com, edwardwu@...ltek.com, phelic@...ltek.com,
 shawn.huang724@...ltek.com, cy.huang@...ltek.com, james.tai@...ltek.com,
 cylee12@...ltek.com, phinex@...ltek.com, conor+dt@...nel.org,
 krzk+dt@...nel.org, robh@...nel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, stanley_chang@...ltek.com
Subject: Re: [PATCH v2 2/2] clocksource: Add Realtek systimer as tick
 broadcast driver

On 14/11/2025 10:04, Hao-Wen Ting wrote:
> Add a tick broadcast timer driver for Realtek SoCs.
> 
> On Realtek platforms, CPUs can enter deep idle states (C-states) where
> the local timer is stopped and powered off. Without a global tick
> broadcast timer, one CPU must remain awake to wake up the others,
> preventing all CPUs from entering deep idle simultaneously.
> 
> This driver provides a tick broadcast timer which remains active
> during deep idle states. This allows all CPUs to enter power-cut
> idle states simultaneously, significantly reducing overall power
> consumption.
> 
> The timer operates at 1MHz and supports oneshot mode.
> 
> Signed-off-by: Hao-Wen Ting <haowen.ting@...ltek.com>
> ---
>  MAINTAINERS                         |   5 +
>  drivers/clocksource/Kconfig         |  10 ++
>  drivers/clocksource/Makefile        |   1 +
>  drivers/clocksource/timer-realtek.c | 172 ++++++++++++++++++++++++++++
>  4 files changed, 188 insertions(+)
>  create mode 100644 drivers/clocksource/timer-realtek.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c7a116b795d5..90f511bb4982 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21670,6 +21670,11 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/spi/realtek,rtl9301-snand.yaml
>  F:	drivers/spi/spi-realtek-rtl-snand.c
>  
> +REALTEK SYSTIMER DRIVER
> +M:	Hao-Wen Ting <haowen.ting@...ltek.com>
> +S:	Maintained
> +F:	drivers/clocksource/timer-realtek.c
> +
>  REALTEK WIRELESS DRIVER (rtlwifi family)
>  M:	Ping-Ke Shih <pkshih@...ltek.com>
>  L:	linux-wireless@...r.kernel.org
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index ffcd23668763..0c1835b48a18 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -782,4 +782,14 @@ config NXP_STM_TIMER
>            Enables the support for NXP System Timer Module found in the
>            s32g NXP platform series.
>  
> +config RTK_SYSTIMER
> +	bool "Realtek SYSTIMER support"
> +	depends on ARM || ARM64


No, I asked to depend on specific SoC ARCH. Not top level architecture.
Also, each such dependency must have compile test, just look at other code.

Best regards,
Krzysztof