linux-kernel - Re: [PATCH v1 1/2] usb: dwc3: Refactor usb-psy init

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Date: Fri, 22 Dec 2023 22:40:23 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Badhri Jagan Sridharan <badhri@...gle.com>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "raychi@...gle.com" <raychi@...gle.com>,
        "royluo@...gle.com" <royluo@...gle.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v1 1/2] usb: dwc3: Refactor usb-psy init

On Sat, Dec 16, 2023, Badhri Jagan Sridharan wrote:
> Move usb-psy init to dwc3_populate_usb_psy() so that gadget can re-use
> it to retry setting up usb-psy when null.
> 
> Cc: stable@...r.kernel.org
> Fixes: 6f0764b5adea ("usb: dwc3: add a power supply for current control")

This is not a fix. It shouldn't go to stable.

> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
> ---
>  drivers/usb/dwc3/core.c | 24 ++++++++++++++++--------
>  drivers/usb/dwc3/core.h |  1 +
>  2 files changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index b101dbf8c5dc..a93425b9c1c0 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1495,6 +1495,19 @@ static void dwc3_core_exit_mode(struct dwc3 *dwc)
>  	dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);
>  }
>  
> +void dwc3_populate_usb_psy(struct dwc3 *dwc)
> +{
> +	const char *usb_psy_name;
> +	int ret;
> +
> +	if (dwc->usb_psy)
> +		return;
> +
> +	ret = device_property_read_string(dwc->dev, "usb-psy-name", &usb_psy_name);
> +	if (ret >= 0)
> +		dwc->usb_psy = power_supply_get_by_name(usb_psy_name);
> +}
> +
>  static void dwc3_get_properties(struct dwc3 *dwc)
>  {
>  	struct device		*dev = dwc->dev;
> @@ -1510,8 +1523,6 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>  	u8			tx_thr_num_pkt_prd = 0;
>  	u8			tx_max_burst_prd = 0;
>  	u8			tx_fifo_resize_max_num;
> -	const char		*usb_psy_name;
> -	int			ret;
>  
>  	/* default to highest possible threshold */
>  	lpm_nyet_threshold = 0xf;
> @@ -1544,12 +1555,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>  	else
>  		dwc->sysdev = dwc->dev;
>  
> -	ret = device_property_read_string(dev, "usb-psy-name", &usb_psy_name);
> -	if (ret >= 0) {
> -		dwc->usb_psy = power_supply_get_by_name(usb_psy_name);
> -		if (!dwc->usb_psy)
> -			dev_err(dev, "couldn't get usb power supply\n");
> -	}
> +	dwc3_populate_usb_psy(dwc);
> +	if (!dwc->usb_psy)
> +		dev_err(dev, "couldn't get usb power supply\n");
>  
>  	dwc->has_lpm_erratum = device_property_read_bool(dev,
>  				"snps,has-lpm-erratum");
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index efe6caf4d0e8..6c65d76e6fe2 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1526,6 +1526,7 @@ struct dwc3_gadget_ep_cmd_params {
>  void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode);
>  void dwc3_set_mode(struct dwc3 *dwc, u32 mode);
>  u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type);
> +void dwc3_populate_usb_psy(struct dwc3 *dwc);
>  
>  #define DWC3_IP_IS(_ip)							\
>  	(dwc->ip == _ip##_IP)
> 
> base-commit: 51920207674e9e3475a91d2091583889792df99a
> -- 
> 2.43.0.472.g3155946c3a-goog
> 

Why do we want to retry again? Perhaps the dwc3 needs to wait for the
power supply available by using -EPROBE_DEFERRED?

BR,
Thinh