linux-kernel - Re: [PATCH v2 1/4] usb: dwc3: core: Introduce glue callbacks for flattened implementations

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Message-ID: <20250623232433.apv23svbaql7ce4u@synopsys.com>
Date: Mon, 23 Jun 2025 23:24:40 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Krishna Kurapati <krishna.kurapati@....qualcomm.com>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Andersson <bjorn.andersson@....qualcomm.com>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/4] usb: dwc3: core: Introduce glue callbacks for
 flattened implementations

On Tue, Jun 10, 2025, Krishna Kurapati wrote:
> In certain situations like role switching, the glue layers need to be
> informed of these events, so that they can take any necessary action.
> But in non-flattened implementations, the glue drivers have no data on
> when the core driver probe was successful post invoking of_platform_
> populate. Now that the core driver supports flattened implementations
> as well, introduce vendor callbacks that can be passed on from glue to
> core before invoking dwc3_core_probe.
> 
> Introduce callbacks to notify glue layer of role_switch and run_stop
> changes. These can be used by flattened implementation of Qualcomm
> glue layer to generate connect/disconnect events in controller during
> cable connect and run stop modifications by udc in device mode.
> 
> Signed-off-by: Krishna Kurapati <krishna.kurapati@....qualcomm.com>
> ---
>  drivers/usb/dwc3/core.c   |  1 +
>  drivers/usb/dwc3/core.h   | 26 ++++++++++++++++++++++++++
>  drivers/usb/dwc3/drd.c    |  1 +
>  drivers/usb/dwc3/gadget.c |  1 +
>  4 files changed, 29 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 2bc775a747f2..c01b15e3710f 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2351,6 +2351,7 @@ static int dwc3_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	dwc->dev = &pdev->dev;
> +	dwc->glue_ops = NULL;
>  
>  	probe_data.dwc = dwc;
>  	probe_data.res = res;
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index d5b985fa12f4..a803884be4ed 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -992,6 +992,17 @@ struct dwc3_scratchpad_array {
>  	__le64	dma_adr[DWC3_MAX_HIBER_SCRATCHBUFS];
>  };
>  
> +/*

Let's keep consistent with the doc style /**

> + * struct dwc3_glue_ops - The ops indicate the notifications that
> + *				need to be passed on to glue layer
> + * @notify_set_role: Notify glue of role switch notifications
> + * @notify_run_stop: Notify run stop enable/disable information to glue
> + */
> +struct dwc3_glue_ops {
> +	void	(*notify_set_role)(struct dwc3 *dwc, enum usb_role role);
> +	void	(*notify_run_stop)(struct dwc3 *dwc, bool is_on);

Use pre_ or prep_ prefix instead of notify_ indicating callbacks for
glue driver to perform updates before set_role or run_stop.

> +};
> +
>  /**
>   * struct dwc3 - representation of our controller
>   * @drd_work: workqueue used for role swapping
> @@ -1168,6 +1179,7 @@ struct dwc3_scratchpad_array {
>   * @wakeup_pending_funcs: Indicates whether any interface has requested for
>   *			 function wakeup in bitmap format where bit position
>   *			 represents interface_id.
> + * @glue_ops: Vendor callbacks for flattened device implementations.
>   */
>  struct dwc3 {
>  	struct work_struct	drd_work;
> @@ -1400,6 +1412,8 @@ struct dwc3 {
>  	struct dentry		*debug_root;
>  	u32			gsbuscfg0_reqinfo;
>  	u32			wakeup_pending_funcs;
> +
> +	struct dwc3_glue_ops	*glue_ops;

Use const, and move this closer on top. Perhaps below gadget_driver.

>  };
>  
>  #define INCRX_BURST_MODE 0
> @@ -1614,6 +1628,18 @@ void dwc3_event_buffers_cleanup(struct dwc3 *dwc);
>  int dwc3_core_soft_reset(struct dwc3 *dwc);
>  void dwc3_enable_susphy(struct dwc3 *dwc, bool enable);
>  
> +static inline void dwc3_notify_set_role(struct dwc3 *dwc, enum usb_role role)
> +{
> +	if (dwc->glue_ops && dwc->glue_ops->notify_set_role)
> +		dwc->glue_ops->notify_set_role(dwc, role);
> +}
> +
> +static inline void dwc3_notify_run_stop(struct dwc3 *dwc, bool is_on)
> +{
> +	if (dwc->glue_ops && dwc->glue_ops->notify_run_stop)
> +		dwc->glue_ops->notify_run_stop(dwc, is_on);
> +}
> +
>  #if IS_ENABLED(CONFIG_USB_DWC3_HOST) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
>  int dwc3_host_init(struct dwc3 *dwc);
>  void dwc3_host_exit(struct dwc3 *dwc);
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index 7977860932b1..408551768a95 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -464,6 +464,7 @@ static int dwc3_usb_role_switch_set(struct usb_role_switch *sw,
>  		break;
>  	}
>  
> +	dwc3_notify_set_role(dwc, role);

This should be done in __dwc3_set_mode(). Perhaps right before setting
PRTCAPDIR?

>  	dwc3_set_mode(dwc, mode);
>  	return 0;
>  }
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 321361288935..73bed11bccaf 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2641,6 +2641,7 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
>  	if (saved_config)
>  		dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
>  
> +	dwc3_notify_run_stop(dwc, is_on);

This should be done right before writing to DCTL.run_stop.

>  	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
>  	if (is_on) {
>  		if (DWC3_VER_IS_WITHIN(DWC3, ANY, 187A)) {
> -- 
> 2.34.1
> 

BR,
Thinh