Re: [PATCH] usb: dwc3: Don't switch OTG -> peripheral if extcon is present

[Thinh Nguyen]

Andrey Smirnov wrote:
> It is necessary that:
> 
>    ROLE_SWITCH && device_property_read_bool(dwc->dev, "usb-role-switch")
> 
> is true in order for dwc3_get_dr_mode() to _not_ force us from OTG to
> PERIPHERAL mode here:
> 
>    if (mode == USB_DR_MODE_OTG &&
>        (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
>         !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
> 	!DWC3_VER_IS_PRIOR(DWC3, 330A))
> 	mode = USB_DR_MODE_PERIPHERAL;
> 
> and dwc3_drd_init() to be called later in dwc3_core_init_mode(). To
> avoid always ignoring extcon device returned by dwc3_get_extcon()
> modify the above check to also account for dwc->edev.
> 

I think the commit message is a bit difficult to follow. Can we rephrase
it to something like this:

If the extcon device exists, get the mode from the extcon device. If the
controller is DRD and the driver is unable to determine the mode, only
then default the dr_mode to USB_DR_MODE_PERIPHERAL.


> Cc: Felipe Balbi <balbi@xxxxxxxxxx>
> Cc: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
> Cc: linux-usb@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
> ---
> 
> Previous discussion:
> 
> https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20220131192102.4115473-1-andrew.smirnov@xxxxxxxxx/__;!!A4F2R9G_pg!OlXelv3-qdUChbfoT9-Qttv4PH8DDro1dSzIj6xEN7x3Vkv8jeh8unvO4RvolUA$ 
> 
>  drivers/usb/dwc3/core.c | 55 ++++++++++++++++++++++++++++++++++++++++-
>  drivers/usb/dwc3/drd.c  | 50 -------------------------------------
>  2 files changed, 54 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index f2448d0a9d39..0ae152e47a00 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -23,6 +23,7 @@
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/of.h>
> +#include <linux/of_graph.h>
>  #include <linux/acpi.h>
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/reset.h>
> @@ -84,7 +85,7 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
>  		 * mode. If the controller supports DRD but the dr_mode is not
>  		 * specified or set to OTG, then set the mode to peripheral.
>  		 */
> -		if (mode == USB_DR_MODE_OTG &&
> +		if (mode == USB_DR_MODE_OTG && !dwc->edev &&
>  		    (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
>  		     !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
>  		    !DWC3_VER_IS_PRIOR(DWC3, 330A))
> @@ -1462,6 +1463,51 @@ static void dwc3_check_params(struct dwc3 *dwc)
>  	}
>  }
> 
> +static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
> +{
> +	struct device *dev = dwc->dev;
> +	struct device_node *np_phy;
> +	struct extcon_dev *edev = NULL;
> +	const char *name;
> +
> +	if (device_property_read_bool(dev, "extcon"))
> +		return extcon_get_edev_by_phandle(dev, 0);
> +
> +	/*
> +	 * Device tree platforms should get extcon via phandle.
> +	 * On ACPI platforms, we get the name from a device property.
> +	 * This device property is for kernel internal use only and
> +	 * is expected to be set by the glue code.
> +	 */
> +	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> +		edev = extcon_get_extcon_dev(name);
> +		if (!edev)
> +			return ERR_PTR(-EPROBE_DEFER);
> +
> +		return edev;
> +	}
> +
> +	/*
> +	 * Try to get an extcon device from the USB PHY controller's "port"
> +	 * node. Check if it has the "port" node first, to avoid printing the
> +	 * error message from underlying code, as it's a valid case: extcon
> +	 * device (and "port" node) may be missing in case of "usb-role-switch"
> +	 * or OTG mode.
> +	 */
> +	np_phy = of_parse_phandle(dev->of_node, "phys", 0);
> +	if (of_graph_is_present(np_phy)) {
> +		struct device_node *np_conn;
> +
> +		np_conn = of_graph_get_remote_node(np_phy, -1, -1);
> +		if (np_conn)
> +			edev = extcon_find_edev_by_node(np_conn);
> +		of_node_put(np_conn);
> +	}
> +	of_node_put(np_phy);
> +
> +	return edev;
> +}
> +
>  static int dwc3_probe(struct platform_device *pdev)
>  {
>  	struct device		*dev = &pdev->dev;
> @@ -1561,6 +1607,13 @@ static int dwc3_probe(struct platform_device *pdev)
>  		goto err2;
>  	}
> 
> +	dwc->edev = dwc3_get_extcon(dwc);
> +	if (IS_ERR(dwc->edev)) {
> +		ret = PTR_ERR(dwc->edev);
> +		dev_err_probe(dwc->dev, ret, "failed to get extcon");

add "\n" ?

> +		goto err3;
> +	}
> +
>  	ret = dwc3_get_dr_mode(dwc);
>  	if (ret)
>  		goto err3;
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index e2b68bb770d1..9a414edc439a 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -8,7 +8,6 @@
>   */
> 
>  #include <linux/extcon.h>
> -#include <linux/of_graph.h>
>  #include <linux/platform_device.h>
>  #include <linux/property.h>
> 
> @@ -438,51 +437,6 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
>  	return NOTIFY_DONE;
>  }
> 
> -static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
> -{
> -	struct device *dev = dwc->dev;
> -	struct device_node *np_phy;
> -	struct extcon_dev *edev = NULL;
> -	const char *name;
> -
> -	if (device_property_read_bool(dev, "extcon"))
> -		return extcon_get_edev_by_phandle(dev, 0);
> -
> -	/*
> -	 * Device tree platforms should get extcon via phandle.
> -	 * On ACPI platforms, we get the name from a device property.
> -	 * This device property is for kernel internal use only and
> -	 * is expected to be set by the glue code.
> -	 */
> -	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> -		edev = extcon_get_extcon_dev(name);
> -		if (!edev)
> -			return ERR_PTR(-EPROBE_DEFER);
> -
> -		return edev;
> -	}
> -
> -	/*
> -	 * Try to get an extcon device from the USB PHY controller's "port"
> -	 * node. Check if it has the "port" node first, to avoid printing the
> -	 * error message from underlying code, as it's a valid case: extcon
> -	 * device (and "port" node) may be missing in case of "usb-role-switch"
> -	 * or OTG mode.
> -	 */
> -	np_phy = of_parse_phandle(dev->of_node, "phys", 0);
> -	if (of_graph_is_present(np_phy)) {
> -		struct device_node *np_conn;
> -
> -		np_conn = of_graph_get_remote_node(np_phy, -1, -1);
> -		if (np_conn)
> -			edev = extcon_find_edev_by_node(np_conn);
> -		of_node_put(np_conn);
> -	}
> -	of_node_put(np_phy);
> -
> -	return edev;
> -}
> -
>  #if IS_ENABLED(CONFIG_USB_ROLE_SWITCH)
>  #define ROLE_SWITCH 1
>  static int dwc3_usb_role_switch_set(struct usb_role_switch *sw,
> @@ -575,10 +529,6 @@ int dwc3_drd_init(struct dwc3 *dwc)
>  {
>  	int ret, irq;
> 
> -	dwc->edev = dwc3_get_extcon(dwc);
> -	if (IS_ERR(dwc->edev))
> -		return PTR_ERR(dwc->edev);
> -
>  	if (ROLE_SWITCH &&
>  	    device_property_read_bool(dwc->dev, "usb-role-switch")) {
>  		ret = dwc3_setup_role_switch(dwc);
> --
> 2.25.1

Reviewed-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>

Thanks,
Thinh