linux-kernel - Re: [PATCH v3 2/3] usb: dwc3: add needs_full

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Message-ID: <aYYPdGKdMdVgfm6x@lizhi-Precision-Tower-5810>
Date: Fri, 6 Feb 2026 10:57:40 -0500
From: Frank Li <Frank.li@....com>
To: Xu Yang <xu.yang_2@....com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, Li Jun <jun.li@....com>,
	Thinh Nguyen <Thinh.Nguyen@...opsys.com>, linux-usb@...r.kernel.org,
	devicetree@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/3] usb: dwc3: add needs_full_reinit flag

On Fri, Feb 06, 2026 at 06:18:50PM +0800, Xu Yang wrote:
> The current design assumes that the controller remains powered when wakeup
> is enabled. However, some SoCs provide wakeup capability even when the
> controller itself is powered down, using separate dedicated wakeup logic.
> This allows additional power savings, but requires the controller to be
> fully re‑initialized after system resume.
>
> To support these SoCs, introduce a flag needs_full_reinit for the purpose.
> And the glue layer needs to indicate if the controller needs this behavior
> by setting a flag core_may_lose_power in dwc3_properties.
>
> Signed-off-by: Xu Yang <xu.yang_2@....com>
Reviewed-by: Frank Li <Frank.Li@....com>
>
> ---
> Changes in v3:
>  - no changes
> Changes in v2:
>  - put core_may_lose_power into dwc3_properties and check it in
>    dwc3_get_software_properties()
>  - rename may_lose_power to needs_full_reinit
> ---
>  drivers/usb/dwc3/core.c | 9 +++++++--
>  drivers/usb/dwc3/core.h | 3 +++
>  drivers/usb/dwc3/glue.h | 3 +++
>  3 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index c07ffe82c850..c5e0a1705b6f 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1675,6 +1675,9 @@ static void dwc3_get_software_properties(struct dwc3 *dwc,
>  	u16 gsbuscfg0_reqinfo;
>  	int ret;
>
> +	if (properties->core_may_lose_power)
> +		dwc->needs_full_reinit = true;
> +
>  	dwc->gsbuscfg0_reqinfo = DWC3_GSBUSCFG0_REQINFO_UNSPECIFIED;
>
>  	if (properties->gsbuscfg0_reqinfo !=
> @@ -2462,7 +2465,8 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  		dwc3_core_exit(dwc);
>  		break;
>  	case DWC3_GCTL_PRTCAP_HOST:
> -		if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(dwc->dev)) {
> +		if (!PMSG_IS_AUTO(msg) &&
> +		    (!device_may_wakeup(dwc->dev) || dwc->needs_full_reinit)) {
>  			dwc3_core_exit(dwc);
>  			break;
>  		}
> @@ -2525,7 +2529,8 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>  		dwc3_gadget_resume(dwc);
>  		break;
>  	case DWC3_GCTL_PRTCAP_HOST:
> -		if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(dwc->dev)) {
> +		if (!PMSG_IS_AUTO(msg) &&
> +		    (!device_may_wakeup(dwc->dev) || dwc->needs_full_reinit)) {
>  			ret = dwc3_core_init_for_resume(dwc);
>  			if (ret)
>  				return ret;
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 08cc6f2b5c23..01d92d680ba4 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1117,6 +1117,8 @@ struct dwc3_glue_ops {
>   * @usb3_lpm_capable: set if hadrware supports Link Power Management
>   * @usb2_lpm_disable: set to disable usb2 lpm for host
>   * @usb2_gadget_lpm_disable: set to disable usb2 lpm for gadget
> + * @needs_full_reinit: set to indicate the core may lose power and need full
> +			initialization during system pm
>   * @disable_scramble_quirk: set if we enable the disable scramble quirk
>   * @u2exit_lfps_quirk: set if we enable u2exit lfps quirk
>   * @u2ss_inp3_quirk: set if we enable P3 OK for U2/SS Inactive quirk
> @@ -1369,6 +1371,7 @@ struct dwc3 {
>  	unsigned		usb3_lpm_capable:1;
>  	unsigned		usb2_lpm_disable:1;
>  	unsigned		usb2_gadget_lpm_disable:1;
> +	unsigned		needs_full_reinit:1;
>
>  	unsigned		disable_scramble_quirk:1;
>  	unsigned		u2exit_lfps_quirk:1;
> diff --git a/drivers/usb/dwc3/glue.h b/drivers/usb/dwc3/glue.h
> index df86e14cb706..d4ea635c92fb 100644
> --- a/drivers/usb/dwc3/glue.h
> +++ b/drivers/usb/dwc3/glue.h
> @@ -12,9 +12,12 @@
>  /**
>   * dwc3_properties: DWC3 core properties
>   * @gsbuscfg0_reqinfo: Value to be programmed in the GSBUSCFG0.REQINFO field
> + * @core_may_lose_power: indicate the controller may not remain power during
> + *			 system pm
>   */
>  struct dwc3_properties {
>  	u32 gsbuscfg0_reqinfo;
> +	bool core_may_lose_power;
>  };
>
>  #define DWC3_DEFAULT_PROPERTIES ((struct dwc3_properties){		\
>
> --
> 2.34.1
>