linux-kernel - Re: [PATCH 3/4] usb: dwc3: core: add a core init flag for device mode resume

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Message-ID: <20240807011347.ucxlxmcikizreioj@synopsys.com>
Date: Wed, 7 Aug 2024 01:13:52 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Frank Li <Frank.Li@....com>
CC: Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
        "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
        "jun.li@....com" <jun.li@....com>, Peter Chen <peter.chen@....com>
Subject: Re: [PATCH 3/4] usb: dwc3: core: add a core init flag for device mode
 resume

On Fri, Jul 12, 2024, Frank Li wrote:
> From: Li Jun <jun.li@....com>
> 
> The runtime resume will happen before system resume if system wakeup by
> device mode wakeup event(e.g, VBUS). Add a flag to avoid init twice.

What's the consequence of going through the resuming sequence twice?
Will this cause any functional issue?

Thanks,
Thinh

> 
> Reviewed-by: Peter Chen <peter.chen@....com>
> Signed-off-by: Li Jun <jun.li@....com>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/usb/dwc3/core.c | 13 +++++++++++++
>  drivers/usb/dwc3/core.h |  1 +
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 734de2a8bd212..d60917fad8c52 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -950,6 +950,8 @@ static void dwc3_core_exit(struct dwc3 *dwc)
>  	dwc3_phy_exit(dwc);
>  	dwc3_clk_disable(dwc);
>  	reset_control_assert(dwc->reset);
> +
> +	dwc->core_inited = false;
>  }
>  
>  static bool dwc3_core_is_valid(struct dwc3 *dwc)
> @@ -1446,6 +1448,8 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  		dwc3_writel(dwc->regs, DWC3_LLUCTL, reg);
>  	}
>  
> +	dwc->core_inited = true;
> +
>  	return 0;
>  
>  err_power_off_phy:
> @@ -2375,6 +2379,15 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>  
>  	switch (dwc->current_dr_role) {
>  	case DWC3_GCTL_PRTCAP_DEVICE:
> +		/*
> +		 * system resume may come after runtime resume
> +		 * e.g. rpm suspend -> pm suspend -> wakeup
> +		 * -> rpm resume -> system resume, so if already
> +		 *  runtime resumed, system resume should skip it.
> +		 */
> +		if (dwc->core_inited)
> +			break;
> +
>  		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 1e561fd8b86e2..8a4bfd9a25b19 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1195,6 +1195,7 @@ struct dwc3 {
>  	struct clk		*utmi_clk;
>  	struct clk		*pipe_clk;
>  
> +	bool			core_inited;
>  	struct reset_control	*reset;
>  
>  	struct usb_phy		*usb2_phy;
> 
> -- 
> 2.34.1
>