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From: Roger Quadros <rogerq@ti.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
	<peter.chen@freescale.com>
Cc: <balbi@kernel.org>, <tony@atomide.com>,
	<gregkh@linuxfoundation.org>, <dan.j.williams@intel.com>,
	<mathias.nyman@linux.intel.com>, <Joao.Pinto@synopsys.com>,
	<jun.li@freescale.com>, <grygorii.strashko@ti.com>,
	<yoshihiro.shimoda.uh@renesas.com>, <robh@kernel.org>,
	<nsekhar@ti.com>, <b-liu@ti.com>, <linux-usb@vger.kernel.org>,
	<linux-omap@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<devicetree@vger.kernel.org>
Subject: Re: [PATCH v10 08/14] usb: otg: add OTG/dual-role core
Date: Fri, 10 Jun 2016 13:54:52 +0300	[thread overview]
Message-ID: <575A9C7C.7020902@ti.com> (raw)
In-Reply-To: <a559997c-2107-1850-1b22-c4532350d665@cogentembedded.com>

On 10/06/16 13:44, Sergei Shtylyov wrote:
> On 6/10/2016 1:19 PM, Roger Quadros wrote:
> 
>>>> It provides APIs for the following tasks
>>>>
>>>> - Registering an OTG/dual-role capable controller
>>>> - Registering Host and Gadget controllers to OTG core
>>>> - Providing inputs to and kicking the OTG state machine
>>>>
>>>> Provide a dual-role device (DRD) state machine.
>>>> DRD mode is a reduced functionality OTG mode. In this mode
>>>> we don't support SRP, HNP and dynamic role-swap.
>>>>
>>>> In DRD operation, the controller mode (Host or Peripheral)
>>>> is decided based on the ID pin status. Once a cable plug (Type-A
>>>> or Type-B) is attached the controller selects the state
>>>> and doesn't change till the cable in unplugged and a different
>>>> cable type is inserted.
>>>>
>>>> As we don't need most of the complex OTG states and OTG timers
>>>> we implement a lean DRD state machine in usb-otg.c.
>>>> The DRD state machine is only interested in 2 hardware inputs
>>>> 'id' and 'b_sess_vld'.
>>>>
>>>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>>>
>>
>> <snip>
>>
>>> [...]
>>>> +/**
>>>> + * usb_otg_register_gadget - Register the gadget controller to OTG core
>>>> + * @gadget:    gadget controller
>>>
>>>    We call that USB device controller (UDC). I'm not sure what you meant here...
>>>    And what about the 2nd arg, 'ops'?
>>
>> There are 2 data structures representing the Device controller.
>>
>> struct usb_gadget - represents a usb slave device
>> struct usb_udc -struct usb_udc - describes one usb device controller
>>
>> usb_udc is for private use only. usb_otg_register_gadget() takes struct usb_gadget
>> as argument.
>>
>> Do you want me to refer to struct usb_gadget as UDC?
> 
>    No.
> 
>> What is wrong with calling it gadget controller?
> 
>    It's not a controller, it's a piece of software AFAIU. Or is my English just too weak? :-)

Everything at this point is a piece of software :).

struct usb_gadget, represents the gadget controller device not the driver (or software).

struct usb_gadget_driver represents the gadget function driver.
struct usb_gadget_ops represents the UDC driver ops.

--
cheers,
-roger

  reply	other threads:[~2016-06-10 10:55 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08  9:03 [PATCH v9 00/14] USB OTG/dual-role framework Roger Quadros
2016-06-08  9:03 ` [PATCH v9 01/14] usb: hcd: Initialize hcd->flags to 0 Roger Quadros
2016-06-08  9:03 ` [PATCH v9 02/14] usb: otg-fsm: Prevent build warning "VDBG" redefined Roger Quadros
2016-06-08  9:03 ` [PATCH v9 03/14] usb: hcd.h: Add OTG to HCD interface Roger Quadros
2016-06-08 11:39   ` Sergei Shtylyov
2016-06-08 12:04     ` Roger Quadros
2016-06-08 12:10       ` Sergei Shtylyov
2016-06-09  7:31         ` Roger Quadros
2016-06-09 10:16           ` Sergei Shtylyov
2016-06-09 14:11             ` Alan Stern
2016-06-10  7:01               ` Roger Quadros
2016-06-09  7:51   ` [PATCH v10 " Roger Quadros
2016-06-08  9:03 ` [PATCH v9 04/14] usb: otg-fsm: use usb_otg wherever possible Roger Quadros
2016-06-08  9:03 ` [PATCH v9 05/14] usb: otg-fsm: move host controller operations into usb_otg->hcd_ops Roger Quadros
2016-06-08  9:03 ` [PATCH v9 06/14] usb: gadget.h: Add OTG to gadget interface Roger Quadros
2016-06-08  9:03 ` [PATCH v9 07/14] usb: otg: get rid of CONFIG_USB_OTG_FSM in favour of CONFIG_USB_OTG Roger Quadros
2016-06-08  9:03 ` [PATCH v9 08/14] usb: otg: add OTG/dual-role core Roger Quadros
2016-06-08  9:53   ` Peter Chen
2016-06-08 10:12     ` Roger Quadros
2016-06-08 12:42       ` Peter Chen
2016-06-09  7:24         ` Roger Quadros
2016-06-12  6:26           ` Peter Chen
2016-06-12 10:56             ` Peter Chen
2016-06-09  7:53   ` [PATCH v10 " Roger Quadros
2016-06-09 12:34     ` Sergei Shtylyov
2016-06-10  7:04       ` Roger Quadros
2016-06-10 10:19       ` Roger Quadros
2016-06-10 10:44         ` Sergei Shtylyov
2016-06-10 10:54           ` Roger Quadros [this message]
2016-06-10 11:02             ` Felipe Balbi
2016-06-08  9:03 ` [PATCH v9 09/14] usb: of: add an API to get OTG device from USB controller node Roger Quadros
2016-06-08  9:03 ` [PATCH v9 10/14] usb: otg: add hcd companion support Roger Quadros
2016-06-08  9:03 ` [PATCH v9 11/14] usb: otg: use dev_dbg() instead of VDBG() Roger Quadros
2016-06-08 15:10   ` Joe Perches
2016-06-09  7:25     ` Roger Quadros
2016-06-09  7:55   ` [PATCH v10 " Roger Quadros
2016-06-09 15:43     ` Joe Perches
2016-06-10  7:05       ` Roger Quadros
2016-06-08  9:03 ` [PATCH v9 12/14] usb: hcd: Adapt to OTG core Roger Quadros
2016-06-08 11:42   ` Sergei Shtylyov
2016-06-08 12:06     ` Roger Quadros
2016-06-08 12:11       ` Sergei Shtylyov
2016-06-09  7:27         ` Roger Quadros
2016-06-08  9:03 ` [PATCH v9 13/14] usb: gadget: udc: adapt " Roger Quadros
2016-06-09 10:49   ` Yoshihiro Shimoda
2016-06-10  7:06     ` Roger Quadros
2016-06-08  9:03 ` [PATCH v9 14/14] usb: host: xhci-plat: Add otg device to platform data Roger Quadros
2016-06-09  5:27 ` [PATCH v9 00/14] USB OTG/dual-role framework Peter Chen
2016-06-09  7:30   ` Roger Quadros
2016-06-09 10:13     ` Yoshihiro Shimoda
2016-06-10 13:07 [PATCH v10 " Roger Quadros
2016-06-10 13:07 ` [PATCH v10 08/14] usb: otg: add OTG/dual-role core Roger Quadros
2016-06-12 11:21   ` Peter Chen
2016-06-13  7:42     ` Roger Quadros

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