Re: [PATCH v4 7/9] usb: dwc3: Registering a role switch in the DRD code.

[Felipe Balbi <balbi@kernel.org>]

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Hi,

John Stultz <john.stultz@linaro.org> writes:
> From: Yu Chen <chenyu56@huawei.com>
>
> The Type-C drivers use USB role switch API to inform the
> system about the negotiated data role, so registering a role
> switch in the DRD code in order to support platforms with
> USB Type-C connectors.
>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> CC: ShuFan Lee <shufan_lee@richtek.com>
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
> Cc: Yu Chen <chenyu56@huawei.com>
> Cc: Felipe Balbi <balbi@kernel.org>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Jun Li <lijun.kernel@gmail.com>
> Cc: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Jack Pham <jackp@codeaurora.org>
> Cc: linux-usb@vger.kernel.org
> Cc: devicetree@vger.kernel.org
> Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Signed-off-by: Yu Chen <chenyu56@huawei.com>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> v2: Fix role_sw and role_switch_default_mode descriptions as
>     reported by kbuild test robot <lkp@intel.com>
>
> v3: Split out the role-switch-default-host logic into its own
>     patch
> ---
>  drivers/usb/dwc3/Kconfig |  1 +
>  drivers/usb/dwc3/core.h  |  3 ++
>  drivers/usb/dwc3/drd.c   | 66 +++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 69 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
> index 89abc6078703..1104745c41a9 100644
> --- a/drivers/usb/dwc3/Kconfig
> +++ b/drivers/usb/dwc3/Kconfig
> @@ -44,6 +44,7 @@ config USB_DWC3_DUAL_ROLE
>  	bool "Dual Role mode"
>  	depends on ((USB=y || USB=USB_DWC3) && (USB_GADGET=y || USB_GADGET=USB_DWC3))
>  	depends on (EXTCON=y || EXTCON=USB_DWC3)
> +	select USB_ROLE_SWITCH

so even those using DWC3 as a peripheral-only or host-only driver will
need role switch?

> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 1c8b349379af..6f19e9891767 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -25,6 +25,7 @@
>  #include <linux/usb/ch9.h>
>  #include <linux/usb/gadget.h>
>  #include <linux/usb/otg.h>
> +#include <linux/usb/role.h>
>  #include <linux/ulpi/interface.h>
>  
>  #include <linux/phy/phy.h>
> @@ -951,6 +952,7 @@ struct dwc3_scratchpad_array {
>   * @hsphy_mode: UTMI phy mode, one of following:
>   *		- USBPHY_INTERFACE_MODE_UTMI
>   *		- USBPHY_INTERFACE_MODE_UTMIW
> + * @role_sw: usb_role_switch handle
>   * @usb2_phy: pointer to USB2 PHY
>   * @usb3_phy: pointer to USB3 PHY
>   * @usb2_generic_phy: pointer to USB2 PHY
> @@ -1084,6 +1086,7 @@ struct dwc3 {
>  	struct extcon_dev	*edev;
>  	struct notifier_block	edev_nb;
>  	enum usb_phy_interface	hsphy_mode;
> +	struct usb_role_switch	*role_sw;
>  
>  	u32			fladj;
>  	u32			irq_gadget;
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index c946d64142ad..61d4fd8aead4 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -476,6 +476,52 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
>  	return edev;
>  }
>  
> +static int dwc3_usb_role_switch_set(struct device *dev, enum usb_role role)
> +{
> +	struct dwc3 *dwc = dev_get_drvdata(dev);
> +	u32 mode;
> +
> +	switch (role) {
> +	case USB_ROLE_HOST:
> +		mode = DWC3_GCTL_PRTCAP_HOST;
> +		break;
> +	case USB_ROLE_DEVICE:
> +		mode = DWC3_GCTL_PRTCAP_DEVICE;
> +		break;
> +	default:
> +		mode = DWC3_GCTL_PRTCAP_DEVICE;
> +		break;
> +	}
> +
> +	dwc3_set_mode(dwc, mode);
> +	return 0;
> +}

role switching is starting to get way too complicated in DWC3. We now
have a function that queues a work on the system_freezable_wq that will
configure PHY and change PRTCAP. Is there a way we can simplify some of
this a little?

-- 
balbi

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