Message-ID: <5762887A.4060606@ti.com>
Date:	Thu, 16 Jun 2016 14:07:38 +0300
From:	Roger Quadros <rogerq@...com>
To:	<balbi@...nel.org>
CC:	<peter.chen@...escale.com>, <tony@...mide.com>,
	<gregkh@...uxfoundation.org>, <dan.j.williams@...el.com>,
	<mathias.nyman@...ux.intel.com>, <Joao.Pinto@...opsys.com>,
	<sergei.shtylyov@...entembedded.com>, <jun.li@...escale.com>,
	<grygorii.strashko@...com>, <yoshihiro.shimoda.uh@...esas.com>,
	<robh@...nel.org>, <nsekhar@...com>, <b-liu@...com>,
	<joe@...ches.com>, <linux-usb@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH v10 00/14] USB OTG/dual-role framework

Hi Felipe,

On 10/06/16 16:07, 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.

Do you have any comments on this series? If yes I can include them
before sending v11 with Acks from Peter and Alan. Thanks.

--
cheers,
-roger

> 
> DWC3 controller and TI platform related patches will be sent separately.
> 
> Series is based on v4.7-rc1 + balbi/usb.git testing/next
> commit 4a2786c10462df650965785462ca82c185164d98.
> 
> 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);
> 
> - The following function is provided for use by the USB gadget stack
> to notify OTG/DRD about gadget function driver being ready/not-ready
> 	int usb_otg_gadget_ready(struct usb_gadget *gadget, bool ready)
> 
> Changelog:
> ---------
> v10:
> - added missing mutex_unlock in failure path in usb_otg_unregister()
> - removed unnecessary hrtimer.h and ktime.h in linux/usb/otg.h
> - comment fixes: urb->URB.
> - fix commit log: say dev_vdbg() instead of dev_dbg().
> - Update comments so that HCD means Host Controller Driver.
> - rebased on Felipe's balbi/usb.git /testing/next
> - include <linux/usb/of.h> in usb-otg.c
> - in usb_otg_start_host() check if hcd_ops->add() failed and return
> error code if it did.
> - in usb_otg_start/stop_gadget() check if hcd_ops->add() failed and return
> error code if it did.
> - follow kernel-doc style in usb-otg.c
> 
> v9:
> - In the DT bindings, clearly indicate which properties are for OTG controller
> and which ones are for host/device controllers
> - Removed host/gadget wait list from otg core. Use defer probing if host/gadget
> registers before dual-role/otg controller.
> - move gadget registering to otg core from udc_bind_to_driver()/usb_gadget_remove_driver()
> to usb_add_gadget_udc_release()/usb_del_gadget_udc(). This means that we need
> an additional mechanism to know when the gadget function driver registers.
> So we add usb_otg_gadget_ready() API to allow gadget to notify otg core about
> ready/not-ready function driver.
> - update otg->caps based on capabilities provided by the controller and the
> device tree overrides.
> - in usb_drd_work() we must keep calling the drd_statemachine() as long as
> there is a state change.
> - updated kconfig so that usbotg can be a module when both host and gadget
> are modules.
> - rebased on v4.7-rc1
> 
> v8:
> - split out start/stop gadget and connect/disconnect operations.
> - make CONFIG_OTG dpend on CONFIG_USB_GADGET as well apart from CONFIG_USB
> - use create_freezable_workqueue() for OTG work as per Peter's suggestion.
> - remove usb-otg.h as we're not initializing any OTG timers.
> - don't include unnecessary headers in usb-otg.c (i.e. hrtimer.h & ktime.h)
> 
> 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.
> 
> 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_vdbg() 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/Kconfig                               |  18 +
>  drivers/usb/Makefile                              |   1 +
>  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                       |   5 +-
>  drivers/usb/common/common.c                       |  27 +
>  drivers/usb/common/usb-otg-fsm.c                  | 203 ++---
>  drivers/usb/common/usb-otg.c                      | 919 ++++++++++++++++++++++
>  drivers/usb/core/Kconfig                          |  22 -
>  drivers/usb/core/hcd.c                            |  56 ++
>  drivers/usb/gadget/Kconfig                        |   1 +
>  drivers/usb/gadget/udc/core.c                     | 202 ++++-
>  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                        |  22 +
>  include/linux/usb/hcd.h                           |  29 +
>  include/linux/usb/of.h                            |   9 +
>  include/linux/usb/otg-fsm.h                       | 154 +---
>  include/linux/usb/otg.h                           | 290 ++++++-
>  include/linux/usb/xhci_pdriver.h                  |   3 +
>  29 files changed, 1918 insertions(+), 462 deletions(-)
>  create mode 100644 drivers/usb/common/usb-otg.c
> 

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