Re: [PATCH] usb: dwc3: gadget: Move vbus draw to workqueue context

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Thu, Jan 29, 2026, Prashanth K wrote:
> Currently dwc3_gadget_vbus_draw() can be called from atomic
> context, which in turn invokes power-supply-core APIs. And
> some these PMIC APIs have operations that may sleep, leading
> to kernel panic.
> 
> Fix this by moving the vbus_draw into a workqueue context.
> 
> Fixes: 66e0ea341a2a ("usb: dwc3: core: Defer the probe until USB power supply ready")
> Cc: stable@vger.kernel.org
> Signed-off-by: Prashanth K <prashanth.k@oss.qualcomm.com>
> ---
>  drivers/usb/dwc3/core.c   | 19 ++++++++++++++++++-
>  drivers/usb/dwc3/core.h   |  4 ++++
>  drivers/usb/dwc3/gadget.c |  8 +++-----
>  3 files changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index f32b67bf73a4..c9af126b9695 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2155,6 +2155,20 @@ static int dwc3_get_num_ports(struct dwc3 *dwc)
>  	return 0;
>  }
>  
> +static void dwc3_vbus_draw_work(struct work_struct *work)
> +{
> +	struct dwc3 *dwc = container_of(work, struct dwc3, vbus_draw_work);
> +	union power_supply_propval val = {0};
> +	int ret;
> +
> +	val.intval = 1000 * (dwc->vbus_draw_current);
> +	ret = power_supply_set_property(dwc->usb_psy, POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, &val);
> +
> +	if (ret < 0)
> +		dev_dbg(dwc->dev, "Error (%d) setting vbus draw (%d mA)\n",
> +			ret, dwc->vbus_draw_current);
> +}
> +
>  static struct power_supply *dwc3_get_usb_power_supply(struct dwc3 *dwc)
>  {
>  	struct power_supply *usb_psy;
> @@ -2169,6 +2183,7 @@ static struct power_supply *dwc3_get_usb_power_supply(struct dwc3 *dwc)
>  	if (!usb_psy)
>  		return ERR_PTR(-EPROBE_DEFER);
>  
> +	INIT_WORK(&dwc->vbus_draw_work, dwc3_vbus_draw_work);
>  	return usb_psy;
>  }
>  
> @@ -2395,8 +2410,10 @@ void dwc3_core_remove(struct dwc3 *dwc)
>  
>  	dwc3_free_event_buffers(dwc);
>  
> -	if (dwc->usb_psy)
> +	if (dwc->usb_psy) {
> +		cancel_work_sync(&dwc->vbus_draw_work);
>  		power_supply_put(dwc->usb_psy);
> +	}
>  }
>  EXPORT_SYMBOL_GPL(dwc3_core_remove);
>  
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 08cc6f2b5c23..052fb18c6b5c 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1178,6 +1178,8 @@ struct dwc3_glue_ops {
>   * @wakeup_pending_funcs: Indicates whether any interface has requested for
>   *			 function wakeup in bitmap format where bit position
>   *			 represents interface_id.
> + * @vbus_draw_work: Workqueue used for scheduling vbus draw work

This is "work" and not workqueue, and it's used to set the vbus drawing
limit. Move this below usb_psy.

> + * @vbus_draw_current: How much current to draw from vbus, in milliAmperes.

Can we rename this to current_limit to match the setting name? And move
this along with the above.

The rest looks fine to me.

Thanks,
Thinh

>   */
>  struct dwc3 {
>  	struct work_struct	drd_work;
> @@ -1413,6 +1415,8 @@ struct dwc3 {
>  	struct dentry		*debug_root;
>  	u32			gsbuscfg0_reqinfo;
>  	u32			wakeup_pending_funcs;
> +	struct work_struct	vbus_draw_work;
> +	unsigned int		vbus_draw_current;
>  };
>  
>  #define INCRX_BURST_MODE 0
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 9355c952c140..03d8a3a151e0 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3124,8 +3124,6 @@ static void dwc3_gadget_set_ssp_rate(struct usb_gadget *g,
>  static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
>  {
>  	struct dwc3		*dwc = gadget_to_dwc(g);
> -	union power_supply_propval	val = {0};
> -	int				ret;
>  
>  	if (dwc->usb2_phy)
>  		return usb_phy_set_power(dwc->usb2_phy, mA);
> @@ -3133,10 +3131,10 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
>  	if (!dwc->usb_psy)
>  		return -EOPNOTSUPP;
>  
> -	val.intval = 1000 * mA;
> -	ret = power_supply_set_property(dwc->usb_psy, POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, &val);
> +	dwc->vbus_draw_current = mA;
> +	schedule_work(&dwc->vbus_draw_work);
>  
> -	return ret;
> +	return 0;
>  }
>  
>  /**
> -- 
> 2.34.1
>