linux-kernel - Re: [PATCH] usb: dwc2: disable platform lowlevel hw resources during shutdown

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Message-ID: <cd7a3c4a-13fd-c87a-e410-48927f76a7b0@synopsys.com>
Date: Mon, 30 Jun 2025 06:40:01 +0000
From: Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To: Jisheng Zhang <jszhang@...nel.org>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc2: disable platform lowlevel hw resources during
 shutdown



On 6/29/25 13:46, Jisheng Zhang wrote:
> On some SoC platforms, in shutdown stage, most components' power is cut
> off, but there's still power supply to the so called always-on
> domain, so if the dwc2's regulator is from the always-on domain, we
> need to explicitly disable it to save power.
> 
> Disable platform lowlevel hw resources such as phy, clock and
> regulators etc. in device shutdown hook to reduce non-necessary power
> consumption when the platform enters shutdown stage.
> 
> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>

Acked-by: Minas Harutyunyan <hminas@...opsys.com>

> ---
>   drivers/usb/dwc2/platform.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
> index 12b4dc07d08a..3f83ecc9fc23 100644
> --- a/drivers/usb/dwc2/platform.c
> +++ b/drivers/usb/dwc2/platform.c
> @@ -371,6 +371,9 @@ static void dwc2_driver_shutdown(struct platform_device *dev)
>   
>   	dwc2_disable_global_interrupts(hsotg);
>   	synchronize_irq(hsotg->irq);
> +
> +	if (hsotg->ll_hw_enabled)
> +		dwc2_lowlevel_hw_disable(hsotg);
>   }
>   
>   /**