[PATCH v4 2/7] usb: dwc3: Switch to device mode on gadget start

[Caleb Connolly]

Hi Sjoerd,

On 12/01/2024 08:52, Sjoerd Simons wrote:
> When dr_mode is "otg" the dwc3 is initially configured in _OTG mode;
> However in this mode the gadget functionality doesn't work without
> further configuration. To resolve that on gadget start switch to _DEVICE
> mode globally and go back to _OTG on stop again.
> 
> For this the dwc3_set_mode is renamed to dwc3_core_set_mode to avoid a
> conflict with the same function exposed by xhci-dwc3

I think exporting dwc3_core_set_mode() is probably sensible here. But
I'm not so sure on calling it from dwc3_gadget_start(), that's making
assumptions about board specific implementation details - some boards
might require additional configuration to switch into gadget mode.

What about calling dwc3_core_set_mode() from within your board-specific
board_usb_init() function?

Obviously as you said the ideal solution here is that we can correctly
traverse the type-c connector model from within U-Boot, but that's a
whole other kettle of fish :P

On Qualcomm platforms I'm currently handling this by overriding the
dr_mode property in a <board>-u-boot.dtsi file, if you aren't using the
same DT for U-Boot and Linux then maybe this would be acceptable for you
too?

Kind regards,
> 
> Signed-off-by: Sjoerd Simons <sjoerd at collabora.com>
> 
> ---
> 
> Changes in v4:
> - New patch
> 
>  drivers/usb/dwc3/core.c   | 10 +++++-----
>  drivers/usb/dwc3/core.h   |  1 +
>  drivers/usb/dwc3/gadget.c |  6 ++++++
>  3 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 4b4fcd8a22e..d22d4c4bb6a 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -42,7 +42,7 @@
>  static LIST_HEAD(dwc3_list);
>  /* -------------------------------------------------------------------------- */
>  
> -static void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
> +void dwc3_core_set_mode(struct dwc3 *dwc, u32 mode)
>  {
>  	u32 reg;
>  
> @@ -736,7 +736,7 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
>  
>  	switch (dwc->dr_mode) {
>  	case USB_DR_MODE_PERIPHERAL:
> -		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
> +		dwc3_core_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
>  		ret = dwc3_gadget_init(dwc);
>  		if (ret) {
>  			dev_err(dwc->dev, "failed to initialize gadget\n");
> @@ -744,7 +744,7 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
>  		}
>  		break;
>  	case USB_DR_MODE_HOST:
> -		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_HOST);
> +		dwc3_core_set_mode(dwc, DWC3_GCTL_PRTCAP_HOST);
>  		ret = dwc3_host_init(dwc);
>  		if (ret) {
>  			dev_err(dwc->dev, "failed to initialize host\n");
> @@ -752,7 +752,7 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
>  		}
>  		break;
>  	case USB_DR_MODE_OTG:
> -		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
> +		dwc3_core_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
>  		ret = dwc3_host_init(dwc);
>  		if (ret) {
>  			dev_err(dwc->dev, "failed to initialize host\n");
> @@ -810,7 +810,7 @@ static void dwc3_core_exit_mode(struct dwc3 *dwc)
>  	 * switch back to peripheral mode
>  	 * This enables the phy to enter idle and then, if enabled, suspend.
>  	 */
> -	dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
> +	dwc3_core_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
>  	dwc3_gadget_run(dwc);
>  }
>  
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 4162a682298..1e7eda89a34 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1057,6 +1057,7 @@ int dwc3_gadget_resize_tx_fifos(struct dwc3 *dwc);
>  void dwc3_of_parse(struct dwc3 *dwc);
>  int dwc3_init(struct dwc3 *dwc);
>  void dwc3_remove(struct dwc3 *dwc);
> +void dwc3_core_set_mode(struct dwc3 *dwc, u32 mode);
>  
>  static inline int dwc3_host_init(struct dwc3 *dwc)
>  { return 0; }
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 406d36ceafe..69d9fe40e2f 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1468,6 +1468,9 @@ static int dwc3_gadget_start(struct usb_gadget *g,
>  
>  	dwc->gadget_driver	= driver;
>  
> +	if (dwc->dr_mode == DWC3_GCTL_PRTCAP_OTG)
> +		dwc3_core_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
> +
>  	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
>  	reg &= ~(DWC3_DCFG_SPEED_MASK);
>  
> @@ -1559,6 +1562,9 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
>  	__dwc3_gadget_ep_disable(dwc->eps[0]);
>  	__dwc3_gadget_ep_disable(dwc->eps[1]);
>  
> +	if (dwc->dr_mode == DWC3_GCTL_PRTCAP_OTG)
> +		dwc3_core_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
> +
>  	dwc->gadget_driver	= NULL;
>  
>  	spin_unlock_irqrestore(&dwc->lock, flags);

-- 
// Caleb (they/them)