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

From: Felipe Balbi
Date: Tue Oct 29 2019 - 05:22:00 EST



Hi,

John Stultz <john.stultz@xxxxxxxxxx> writes:
> From: Yu Chen <chenyu56@xxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> CC: ShuFan Lee <shufan_lee@xxxxxxxxxxx>
> Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Cc: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> Cc: Yu Chen <chenyu56@xxxxxxxxxx>
> Cc: Felipe Balbi <balbi@xxxxxxxxxx>
> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Cc: Jun Li <lijun.kernel@xxxxxxxxx>
> Cc: Valentin Schneider <valentin.schneider@xxxxxxx>
> Cc: Jack Pham <jackp@xxxxxxxxxxxxxx>
> Cc: linux-usb@xxxxxxxxxxxxxxx
> Cc: devicetree@xxxxxxxxxxxxxxx
> Suggested-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx>
> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> ---
> v2: Fix role_sw and role_switch_default_mode descriptions as
> reported by kbuild test robot <lkp@xxxxxxxxx>
>
> 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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