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Date: Thu, 3 Dec 2015 14:24:10 +0530 From: Roger Quadros <rogerq@...com> To: Peter Chen <peter.chen@...escale.com> CC: <stern@...land.harvard.edu>, <balbi@...com>, <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>, <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org> Subject: Re: [PATCH v4 00/13] USB: OTG/DRD Core functionality Peter, On 03/12/15 13:49, Peter Chen wrote: > On Mon, Aug 24, 2015 at 04:21:11PM +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 Greg's usb-next tree. > > Hi Roger, > > Will you go on for this patch set? Yes, but I can only work on this from Feb onwards. cheers, -roger > > Peter >> >> Changelog: >> --------- >> 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. >> >> Why?: >> ---- >> >> Most of the OTG drivers have been dealing with the OTG state machine >> themselves and there is a scope for code re-use. This has been >> partly addressed by the usb/common/usb-otg-fsm.c but it still >> leaves the instantiation of the state machine and OTG timers >> to the controller drivers. We re-use usb-otg-fsm.c but >> go one step further by instantiating the state machine and timers >> thus making it easier for drivers to implement OTG functionality. >> >> 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 in OTG mode. i.e. to stop and start them from a >> central location. This central location should be the USB OTG 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 can't be done as of now and can be done from the OTG core. >> >> What?: >> ----- >> >> The OTG core instantiates the OTG/DRD Finite State Machine >> per OTG controller and manages starting/stopping the >> host and gadget controllers based on the bus state. >> >> It provides APIs for the following >> >> - Registering an OTG capable controller >> struct otg_fsm *usb_otg_register(struct device *dev, >> struct usb_otg_config *config); >> >> int usb_otg_unregister(struct device *dev); >> >> - Registering Host controllers to OTG core (used by hcd-core) >> int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum, >> unsigned long irqflags, struct otg_hcd_ops *ops); >> int usb_otg_unregister_hcd(struct usb_hcd *hcd); >> >> >> - Registering Gadget controllers to OTG core (used by udc-core) >> int usb_otg_register_gadget(struct usb_gadget *gadget, >> struct otg_gadget_ops *ops); >> int usb_otg_unregister_gadget(struct usb_gadget *gadget); >> >> >> - Providing inputs to and kicking the OTG state machine >> void usb_otg_sync_inputs(struct otg_fsm *fsm); >> int usb_otg_kick_fsm(struct device *hcd_gcd_device); >> >> - Getting controller device structure from OTG state machine instance >> struct device *usb_otg_fsm_to_dev(struct otg_fsm *fsm); >> >> 'struct otg_fsm' is the interface to the OTG state machine. >> It contains inputs to the fsm, status of the fsm and operations >> for the OTG controller driver. >> >> - Helper APIs for starting/stopping host/gadget controllers >> int usb_otg_start_host(struct otg_fsm *fsm, int on); >> int usb_otg_start_gadget(struct otg_fsm *fsm, int on); >> >> Usage model: >> ----------- >> >> - The OTG core needs to know what host and gadget controllers are >> linked to the OTG controller. For DT boots we can provide that >> information by adding "otg-controller" property to the host and >> gadget controller nodes that points to the right otg controller. >> For legacy boot we assume that OTG controller is the parent >> of the host and gadget controllers. For DT if "otg-controller" >> property is not present then parent child relationship constraint >> applies. >> >> - The OTG controller driver must call usb_otg_register() to register >> itself with the OTG core. It must also provide the required >> OTG configuration, fsm operations and timer timeouts (optional) >> via struct usb_otg_config. The fsm operations will be called >> depending on the OTG bus state. >> >> - The host/gadget core stacks are modified to inform the OTG core >> whenever a new host/gadget device is added. The OTG core then >> checks if the host/gadget is part of the OTG controller and if yes >> then prevents the host/gadget from starting till both host and >> gadget are registered, OTG state machine is running and the >> USB bus state is appropriate to start host/gadget. >> For this, APIs have been added to host/gadget stacks to start/stop >> the controllers from the OTG core. >> For DT boots, If the OTG controller hasn't yet been registered >> while the host/gadget are added, the OTG core will hold it in a wait list >> and register them when the OTG controller registers. >> >> - No modification is needed for the host/gadget controller drivers. >> They must ensure that their start/stop methods can be called repeatedly >> and any shared resources between host & gadget are properly managed. >> The OTG core ensures that both are not started simultaneously. >> >> - The OTG core instantiates one OTG state machine per OTG controller >> and the necessary OTG timers to manage OTG state timeouts. >> If none of the otg features are set during usb_otg_register() then it >> instanciates a DRD (dual-role device) state machine instead. >> The state machine is started when both host & gadget register and >> stopped when either of them unregisters. The controllers are started >> and stopped depending on bus state. >> >> - During the lifetime of the OTG state machine, inputs can be >> provided to it by modifying the appropriate members of 'struct otg_fsm' >> and calling usb_otg_sync_inputs(). This is typically done by the >> OTG controller driver that called usb_otg_register(). >> >> -- >> cheers, >> -roger >> >> Roger Quadros (13): >> usb: otg-fsm: Add documentation for struct otg_fsm >> usb: otg-fsm: support multiple instances >> usb: otg-fsm: Prevent build warning "VDBG" redefined >> otg-fsm: move usb_bus_start_enum into otg-fsm->ops >> usb: hcd.h: Add OTG to HCD interface >> usb: gadget.h: Add OTG to gadget interface >> usb: otg: add OTG core >> usb: doc: dt-binding: Add otg-controller property >> usb: chipidea: move from CONFIG_USB_OTG_FSM to CONFIG_USB_OTG >> usb: hcd: Adapt to OTG core >> usb: core: hub: Notify OTG fsm when A device sets b_hnp_enable >> usb: gadget: udc: adapt to OTG core >> usb: otg: Add dual-role device (DRD) support >> >> Documentation/devicetree/bindings/usb/generic.txt | 5 + >> Documentation/usb/chipidea.txt | 2 +- >> MAINTAINERS | 4 +- >> drivers/usb/Kconfig | 2 +- >> drivers/usb/Makefile | 1 + >> drivers/usb/chipidea/Makefile | 2 +- >> drivers/usb/chipidea/ci.h | 2 +- >> drivers/usb/chipidea/otg_fsm.c | 1 + >> drivers/usb/chipidea/otg_fsm.h | 2 +- >> drivers/usb/common/Makefile | 3 +- >> drivers/usb/common/usb-otg-fsm.c | 26 +- >> drivers/usb/common/usb-otg.c | 1223 +++++++++++++++++++++ >> drivers/usb/common/usb-otg.h | 71 ++ >> drivers/usb/core/Kconfig | 11 +- >> drivers/usb/core/hcd.c | 55 +- >> drivers/usb/core/hub.c | 10 +- >> drivers/usb/gadget/udc/udc-core.c | 124 ++- >> drivers/usb/phy/Kconfig | 2 +- >> drivers/usb/phy/phy-fsl-usb.c | 3 + >> include/linux/usb/gadget.h | 14 + >> include/linux/usb/hcd.h | 14 + >> include/linux/usb/otg-fsm.h | 116 +- >> include/linux/usb/otg.h | 191 +++- >> 23 files changed, 1808 insertions(+), 76 deletions(-) >> create mode 100644 drivers/usb/common/usb-otg.c >> create mode 100644 drivers/usb/common/usb-otg.h >> >> -- >> 2.1.4 >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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