Re: [PATCH v3] usb: dwc3: qcom: Remove extcon functionality from glue

[Prashanth K <prashanth.k@oss.qualcomm.com>]

On 7/14/2025 10:17 AM, Krishna Kurapati wrote:
> Deprecate usage of extcon functionality from the glue driver. Now
> that the glue driver is a flattened implementation, all existing
> DTs would eventually move to new bindings. While doing so let them
> make use of role-switch/ typec frameworks to provide role data
> rather than using extcon.
> 
> On upstream, summary of targets/platforms using extcon is as follows:
> 
> 1. MSM8916 and MSM8939 use Chipidea controller, hence the changes have no
> effect on them.
> 
> 2. Of the other extcon users, most of them use "linux,extcon-usb-gpio"
> driver which relies on id/vbus gpios to inform role changes. This can be
> transitioned to role switch based driver (usb-conn-gpio) while flattening
> those platforms to move away from extcon and rely on role
> switching.
> 
> 3. The one target that uses dwc3 controller and extcon and is not based
> on reading gpios is "arch/arm64/boot/dts/qcom/msm8996-xiaomi-common.dtsi".
> This platform uses TI chip to provide extcon. If usb on this platform is
> being flattneed, then effort should be put in to define a usb-c-connector
> device in DT and make use of role switch functionality in TUSB320L driver.
> 
> Signed-off-by: Krishna Kurapati <krishna.kurapati@oss.qualcomm.com>
> ---
> Changes in v3:
> This change was 4rth patch in [1]. It was suggested to make this as the
> first patch of the series. Since this is independent of role switch
> patches, sending this out separately. Removed RB Tag of Dmitry since the
> patch has been changed.
> 
> [1]: https://lore.kernel.org/all/20250610091357.2983085-1-krishna.kurapati@oss.qualcomm.com/
> 
>  drivers/usb/dwc3/dwc3-qcom.c | 90 +-----------------------------------
>  1 file changed, 1 insertion(+), 89 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index ca7e1c02773a..a7eaefaeec4d 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -11,7 +11,6 @@
>  #include <linux/of_clk.h>
>  #include <linux/module.h>
>  #include <linux/kernel.h>
> -#include <linux/extcon.h>
>  #include <linux/interconnect.h>
>  #include <linux/platform_device.h>
>  #include <linux/phy/phy.h>
> @@ -79,11 +78,6 @@ struct dwc3_qcom {
>  	struct dwc3_qcom_port	ports[DWC3_QCOM_MAX_PORTS];
>  	u8			num_ports;
>  
> -	struct extcon_dev	*edev;
> -	struct extcon_dev	*host_edev;
> -	struct notifier_block	vbus_nb;
> -	struct notifier_block	host_nb;
> -
>  	enum usb_dr_mode	mode;
>  	bool			is_suspended;
>  	bool			pm_suspended;
> @@ -119,8 +113,7 @@ static inline void dwc3_qcom_clrbits(void __iomem *base, u32 offset, u32 val)
>  
>  /*
>   * TODO: Make the in-core role switching code invoke dwc3_qcom_vbus_override_enable(),
> - * validate that the in-core extcon support is functional, and drop extcon
> - * handling from the glue
> + * validate that the in-core extcon support is functional
>   */
>  static void dwc3_qcom_vbus_override_enable(struct dwc3_qcom *qcom, bool enable)
>  {
> @@ -137,80 +130,6 @@ static void dwc3_qcom_vbus_override_enable(struct dwc3_qcom *qcom, bool enable)
>  	}
>  }
>  
> -static int dwc3_qcom_vbus_notifier(struct notifier_block *nb,
> -				   unsigned long event, void *ptr)
> -{
> -	struct dwc3_qcom *qcom = container_of(nb, struct dwc3_qcom, vbus_nb);
> -
> -	/* enable vbus override for device mode */
> -	dwc3_qcom_vbus_override_enable(qcom, event);
> -	qcom->mode = event ? USB_DR_MODE_PERIPHERAL : USB_DR_MODE_HOST;
> -
> -	return NOTIFY_DONE;
> -}
> -
> -static int dwc3_qcom_host_notifier(struct notifier_block *nb,
> -				   unsigned long event, void *ptr)
> -{
> -	struct dwc3_qcom *qcom = container_of(nb, struct dwc3_qcom, host_nb);
> -
> -	/* disable vbus override in host mode */
> -	dwc3_qcom_vbus_override_enable(qcom, !event);
> -	qcom->mode = event ? USB_DR_MODE_HOST : USB_DR_MODE_PERIPHERAL;
> -
> -	return NOTIFY_DONE;
> -}
> -
> -static int dwc3_qcom_register_extcon(struct dwc3_qcom *qcom)
> -{
> -	struct device		*dev = qcom->dev;
> -	struct extcon_dev	*host_edev;
> -	int			ret;
> -
> -	if (!of_property_present(dev->of_node, "extcon"))
> -		return 0;
> -
> -	qcom->edev = extcon_get_edev_by_phandle(dev, 0);
> -	if (IS_ERR(qcom->edev))
> -		return dev_err_probe(dev, PTR_ERR(qcom->edev),
> -				     "Failed to get extcon\n");
> -
> -	qcom->vbus_nb.notifier_call = dwc3_qcom_vbus_notifier;
> -
> -	qcom->host_edev = extcon_get_edev_by_phandle(dev, 1);
> -	if (IS_ERR(qcom->host_edev))
> -		qcom->host_edev = NULL;
> -
> -	ret = devm_extcon_register_notifier(dev, qcom->edev, EXTCON_USB,
> -					    &qcom->vbus_nb);
> -	if (ret < 0) {
> -		dev_err(dev, "VBUS notifier register failed\n");
> -		return ret;
> -	}
> -
> -	if (qcom->host_edev)
> -		host_edev = qcom->host_edev;
> -	else
> -		host_edev = qcom->edev;
> -
> -	qcom->host_nb.notifier_call = dwc3_qcom_host_notifier;
> -	ret = devm_extcon_register_notifier(dev, host_edev, EXTCON_USB_HOST,
> -					    &qcom->host_nb);
> -	if (ret < 0) {
> -		dev_err(dev, "Host notifier register failed\n");
> -		return ret;
> -	}
> -
> -	/* Update initial VBUS override based on extcon state */
> -	if (extcon_get_state(qcom->edev, EXTCON_USB) ||
> -	    !extcon_get_state(host_edev, EXTCON_USB_HOST))
> -		dwc3_qcom_vbus_notifier(&qcom->vbus_nb, true, qcom->edev);
> -	else
> -		dwc3_qcom_vbus_notifier(&qcom->vbus_nb, false, qcom->edev);
> -
> -	return 0;
> -}
> -
>  static int dwc3_qcom_interconnect_enable(struct dwc3_qcom *qcom)
>  {
>  	int ret;
> @@ -737,11 +656,6 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>  	if (qcom->mode != USB_DR_MODE_HOST)
>  		dwc3_qcom_vbus_override_enable(qcom, true);
>  
> -	/* register extcon to override sw_vbus on Vbus change later */
> -	ret = dwc3_qcom_register_extcon(qcom);
> -	if (ret)
> -		goto interconnect_exit;
> -
>  	wakeup_source = of_property_read_bool(dev->of_node, "wakeup-source");
>  	device_init_wakeup(&pdev->dev, wakeup_source);
>  
> @@ -749,8 +663,6 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> -interconnect_exit:
> -	dwc3_qcom_interconnect_exit(qcom);
>  remove_core:
>  	dwc3_core_remove(&qcom->dwc);
>  clk_disable:

Shouldn't we cleanup the Kconfig also? Anyways it's not critical, so it
can be handled in a follow-up patch if preferred.

config USB_DWC3_QCOM
		tristate "Qualcomm Platform"
		depends on ARCH_QCOM || COMPILE_TEST
-		depends on EXTCON || !EXTCON
		depends on OF

Regards,
Prashanth K