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Date: Wed, 11 May 2016 16:36:19 +0800
From: Peter Chen <hzpeterchen@...il.com>
To: Roger Quadros <rogerq@...com>
Cc: peter.chen@...escale.com, stern@...land.harvard.edu,
balbi@...nel.org, gregkh@...uxfoundation.org,
dan.j.williams@...el.com, jun.li@...escale.com,
mathias.nyman@...ux.intel.com, tony@...mide.com,
Joao.Pinto@...opsys.com, abrestic@...omium.org,
yoshihiro.shimoda.uh@...esas.com, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
devicetree@...r.kernel.org
Subject: Re: [PATCH v7 00/14] USB OTG/dual-role framework
On Mon, May 02, 2016 at 03:18:43PM +0300, Roger Quadros wrote:
> Hi,
>
> This series centralizes OTG/Dual-role functionality in the kernel.
> As of now I've got Dual-role functionality working pretty reliably on
> dra7-evm and am437x-gp-evm.
>
> DWC3 controller and platform related patches will be sent separately.
>
> Series is based on v4.6-rc1 and depends on first 2 patches of [1]
> [1] - OTG fsm cleanup - https://lkml.org/lkml/2016/3/30/186
>
> Why?:
> ----
>
> Currently there is no central location where OTG/dual-role functionality is
> implemented in the Linux USB stack and every USB controller driver is
> doing their own thing for OTG/dual-role. We can benefit from code-reuse
> and simplicity by adding the OTG/dual-role core driver.
>
> Newer OTG cores support standard host interface (e.g. xHCI) so
> host and gadget functionality are no longer closely knit like older
> cores. There needs to be a way to co-ordinate the operation of the
> host and gadget controllers in dual-role mode. i.e. to stop and start them
> from a central location. This central location should be the
> USB OTG/dual-role core.
>
> Host and gadget controllers might be sharing resources and can't
> be always running. One has to be stopped for the other to run.
> This couldn't be done till now but can be done from the OTG core.
>
> What?:
> -----
>
> The OTG/dual-role core consists of a set of APIs that allow
> registration of OTG controller device and OTG capable host and gadget
> controllers.
>
> - The OTG controller driver can provide the OTG capabilities and the
> Finite State Machine work function via 'struct usb_otg_config'
> at the time of registration i.e. usb_otg_register();
>
> struct usb_otg *usb_otg_register(struct device *dev,
> struct usb_otg_config *config);
> int usb_otg_unregister(struct device *dev);
> /**
> * struct usb_otg_config - otg controller configuration
> * @caps: otg capabilities of the controller
> * @ops: otg fsm operations
> * @otg_work: optional custom otg state machine work function
> */
> struct usb_otg_config {
> struct usb_otg_caps *otg_caps;
> struct otg_fsm_ops *fsm_ops;
> void (*otg_work)(struct work_struct *work);
> };
>
> The dual-role state machine is built-into the OTG core so nothing
> special needs to be provided if only dual-role functionality is desired.
> The low level OTG controller driver ops are povided via
> 'struct otg_fsm_ops *fsm_ops' in the 'struct usb_otg_config'.
>
> After registration, the OTG core waits for host, gadget controller
> and the gadget function driver to be registered. Once all resources are
> available it instantiates the Finite State Machine (FSM).
> The host/gadget controllers are started/stopped according to the FSM.
>
> - Host and gadget controllers that are a part of OTG/dual-role port must
> use the OTG core provided APIs to add/remove the host/gadget.
> i.e. hosts must use usb_otg_add_hcd() usb_otg_remove_hcd(),,
> gadgets must use usb_otg_add_gadget_udc() usb_del_gadget_udc().
> This ensures that the host and gadget controllers are not started till
> the state machine is ready and the right bus conditions are met.
> It also allows the host and gadget controllers to provide the OTG
> controller device to link them together. For Device tree boots
> the related OTG controller is automatically picked up via the
> 'otg-controller' property in the Host/Gadget controller nodes.
>
> int usb_otg_add_hcd(struct usb_hcd *hcd,
> unsigned int irqnum, unsigned long irqflags,
> struct device *otg_dev);
> void usb_otg_remove_hcd(struct usb_hcd *hcd);
>
> int usb_otg_add_gadget_udc(struct device *parent,
> struct usb_gadget *gadget,
> struct device *otg_dev);
> usb_del_gadget_udc() must be used for removal.
>
>
> - During the lifetime of the FSM, the OTG controller driver can provide
> inputs event changes using usb_otg_sync_inputs(). The OTG core will
> then schedule the FSM work function (or internal dual-role state machine)
> to update the FSM state. The FSM then calls the OTG controller
> operations (fsm_ops) as necessary.
> void usb_otg_sync_inputs(struct usb_otg *otg);
>
> - The following 2 functions are provided as helpers for use by the
> OTG controller driver to start/stop the host/gadget controllers.
> int usb_otg_start_host(struct usb_otg *otg, int on);
> int usb_otg_start_gadget(struct usb_otg *otg, int on);
>
> - The following function is provided for use by the USB host stack
> to sync OTG related events to the OTG state machine.
> e.g. change in host_bus->b_hnp_enable, gadget->b_hnp_enable
> int usb_otg_kick_fsm(struct device *otg_device);
>
> Changelog:
> ---------
> v7:
> - added dual-role support for host controllers requiring a companion
> controller. e.g. EHCI + OHCI.
> - added of_usb_get_otg() to get the OTG controller device
> from the USB controller's device node.
> - addressed review comments.
Would you please list more for review comments, eg which comment for
which part? It is a big patch set, that will let review easy.
Peter
>
> v6:
> - added otg specific APIs for host/gadget registration. behaviour of
> original host/gadget API remains unchanged. Platform devices can now
> pass the otg device explicitly while registering host/gadget.
> - moved hcd specific operations from struct otg_fsm to struct hcd_ops.
> - made struct usb_otg mandatory for all otg related APIs.
> - allow otg controller to provide it's own otg_work function so that
> it can implement it's own state machine.
> - removed otg fsm and timers from usb-otg.c. Only dual-role state machine
> is implemented.
> - vbus is controlled in the dual-role state machine.
> - PM runtime is used around drd_statemachine().
> - added otg_dev to xhci platform data to allow platform code to specify
> the otg controller tied to the xhci host controller.
>
> v5: Internal version. Not sent to mailing list
>
> v4:
> - Added DT support for tying otg-controller to host and gadget
> controllers. For DT we no longer have the constraint that
> OTG controller needs to be parent of host and gadget. They can be
> tied together using the "otg-controller" property.
> - Relax the requirement for DT case that otg controller must register
> before host/gadget. We maintain a wait list of host/gadget devices
> waiting on the otg controller.
> - Use a single struct usb_otg for otg data.
> - Don't override host/gadget start/stop APIs. Let the controller
> drivers do what they want as they know best. Helper API is provided
> for controller start/stop that controller driver can use.
> - Introduce struct usb_otg_config to pass the otg capabilities,
> otg ops and otg timer timeouts during otg controller registration.
> - rebased on Greg's usb.git/usb-next
>
> v3:
> - all otg related definations now in otg.h
> - single kernel config USB_OTG to enable OTG core and FSM.
> - resolved symbol dependency issues.
> - use dev_vdbg instead of VDBG() in usb-otg-fsm.c
> - rebased on v4.2-rc1
>
> v2:
> - Use add/remove_hcd() instead of start/stop_hcd() to enable/disable
> the host controller
> - added dual-role-device (DRD) state machine which is a much simpler
> mode of operation when compared to OTG. Here we don't support fancy
> OTG features like HNP, SRP, on the fly role-swap. The mode of operation
> is determined based on ID pin (cable type) and the role doesn't change
> till the cable type changes.
>
> --
> cheers,
> -roger
>
> Roger Quadros (13):
> usb: hcd: Initialize hcd->flags to 0
> usb: otg-fsm: Prevent build warning "VDBG" redefined
> usb: hcd.h: Add OTG to HCD interface
> usb: otg-fsm: use usb_otg wherever possible
> usb: otg-fsm: move host controller operations into usb_otg->hcd_ops
> usb: gadget.h: Add OTG to gadget interface
> usb: otg: get rid of CONFIG_USB_OTG_FSM in favour of CONFIG_USB_OTG
> usb: otg: add OTG/dual-role core
> usb: of: add an API to get OTG device from USB controller node
> usb: otg: use dev_dbg() instead of VDBG()
> usb: hcd: Adapt to OTG core
> usb: gadget: udc: adapt to OTG core
> usb: host: xhci-plat: Add otg device to platform data
>
> Yoshihiro Shimoda (1):
> usb: otg: add hcd companion support
>
> Documentation/devicetree/bindings/usb/generic.txt | 6 +
> Documentation/usb/chipidea.txt | 2 +-
> drivers/usb/chipidea/Makefile | 2 +-
> drivers/usb/chipidea/ci.h | 3 +-
> drivers/usb/chipidea/core.c | 14 +-
> drivers/usb/chipidea/debug.c | 2 +-
> drivers/usb/chipidea/otg_fsm.c | 176 ++--
> drivers/usb/chipidea/otg_fsm.h | 2 +-
> drivers/usb/chipidea/udc.c | 17 +-
> drivers/usb/common/Makefile | 3 +-
> drivers/usb/common/common.c | 27 +
> drivers/usb/common/usb-otg-fsm.c | 203 ++--
> drivers/usb/common/usb-otg.c | 1054 ++++++++++++++++++++
> .../usb/{chipidea/otg_fsm.h => common/usb-otg.h} | 61 +-
> drivers/usb/core/Kconfig | 10 +-
> drivers/usb/core/hcd.c | 56 ++
> drivers/usb/gadget/udc/udc-core.c | 161 ++-
> drivers/usb/host/xhci-plat.c | 35 +-
> drivers/usb/phy/Kconfig | 2 +-
> drivers/usb/phy/phy-fsl-usb.c | 155 +--
> drivers/usb/phy/phy-fsl-usb.h | 3 +-
> include/linux/usb/gadget.h | 20 +
> include/linux/usb/hcd.h | 29 +
> include/linux/usb/of.h | 9 +
> include/linux/usb/otg-fsm.h | 154 +--
> include/linux/usb/otg.h | 264 ++++-
> include/linux/usb/xhci_pdriver.h | 3 +
> 27 files changed, 1989 insertions(+), 484 deletions(-)
> create mode 100644 drivers/usb/common/usb-otg.c
> copy drivers/usb/{chipidea/otg_fsm.h => common/usb-otg.h} (63%)
>
> --
> 2.7.4
>
> --
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--
Best Regards,
Peter Chen
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