From: Roger Quadros <rogerq@ti.com>
To: Peter Chen <hzpeterchen@gmail.com>
Cc: <peter.chen@freescale.com>, <balbi@kernel.org>,
<tony@atomide.com>, <gregkh@linuxfoundation.org>,
<dan.j.williams@intel.com>, <mathias.nyman@linux.intel.com>,
<Joao.Pinto@synopsys.com>, <sergei.shtylyov@cogentembedded.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 v8 08/14] usb: otg: add OTG/dual-role core
Date: Wed, 25 May 2016 15:21:39 +0300 [thread overview]
Message-ID: <574598D3.5090405@ti.com> (raw)
In-Reply-To: <20160525024427.GA31142@shlinux2>
On 25/05/16 05:44, Peter Chen wrote:
> On Tue, May 24, 2016 at 12:45:46PM +0300, Roger Quadros wrote:
>> Hi Peter,
>>
>> I have one question here. Please see below.
>>
>> On 13/05/16 13:03, 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>
>>> ---
>>> drivers/usb/common/Makefile | 2 +-
>>> drivers/usb/common/usb-otg.c | 1042 ++++++++++++++++++++++++++++++++++++++++++
>>> drivers/usb/core/Kconfig | 4 +-
>>> include/linux/usb/gadget.h | 2 +
>>> include/linux/usb/hcd.h | 1 +
>>> include/linux/usb/otg-fsm.h | 7 +
>>> include/linux/usb/otg.h | 154 ++++++-
>>> 7 files changed, 1206 insertions(+), 6 deletions(-)
>>> create mode 100644 drivers/usb/common/usb-otg.c
>>>
>>
>> <snip>
>>
>>> +
>>> +/**
>>> + * usb_otg_register() - Register the OTG/dual-role device to OTG core
>>> + * @dev: OTG/dual-role controller device.
>>> + * @config: OTG configuration.
>>> + *
>>> + * Registers the OTG/dual-role controller device with the USB OTG core.
>>> + *
>>> + * Return: struct usb_otg * if success, ERR_PTR() if error.
>>> + */
>>> +struct usb_otg *usb_otg_register(struct device *dev,
>>> + struct usb_otg_config *config)
>>> +{
>>> + struct usb_otg *otg;
>>> + struct otg_wait_data *wait;
>>> + int ret = 0;
>>> +
>>> + if (!dev || !config || !config->fsm_ops)
>>> + return ERR_PTR(-EINVAL);
>>> +
>>> + /* already in list? */
>>> + mutex_lock(&otg_list_mutex);
>>> + if (usb_otg_get_data(dev)) {
>>> + dev_err(dev, "otg: %s: device already in otg list\n",
>>> + __func__);
>>> + ret = -EINVAL;
>>> + goto unlock;
>>> + }
>>> +
>>> + /* allocate and add to list */
>>> + otg = kzalloc(sizeof(*otg), GFP_KERNEL);
>>> + if (!otg) {
>>> + ret = -ENOMEM;
>>> + goto unlock;
>>> + }
>>> +
>>> + otg->dev = dev;
>>> + otg->caps = config->otg_caps;
>>
>> Here, we should be checking if user needs to disable any OTG features. So,
>>
>> if (dev->of_node)
>> of_usb_update_otg_caps(dev->of_node, &otg->caps);
>>
>> Do you agree?
>> This means we need to change otg->caps from 'struct usb_otg_caps *caps;'
>> to 'struct usb_otg_caps caps;' so that we can modify the local copy instead
>> of the one passed by the OTG controller.
>
> Why can't modify the one from OTG controller directly?
>
There are 2 things.
1) OTG features supported by hardware. This is the controller's config->otg_caps
2) OTG features needed by system designer. This can be a subset of (1).
This needs to be maintained in the OTG core, based on config->otg_caps and
device tree disable flags.
So we can't use OTG controller config->otg_caps directly.
>>
>> We can also move of_usb_update_otg_caps() to otg.h.
>>
>> We will also need to modify the udc-core code so that it sets gadget->otg_caps
>> to the modified otg_caps from the OTG core. This will ensure that the right
>> OTG descriptors are sent.
>>
>> So we will have to introduce an API.
>>
>> struct usb_otg_caps *usb_otg_get_otg_caps(struct device *otg_dev)
>>
>> And in udc-core.c,
>>
>> static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
>> {
>> ..
>> ret = driver->bind(udc->gadget, driver);
>> if (ret)
>> goto err1;
>>
>> /* If OTG, the otg core starts the UDC when needed */
>> if (udc->gadget->otg_dev) {
>> + udc->gadget->is_otg = true;
>
> gadget->is_otg is only set to true if fully OTG is supported and it
> needs to send OTG descriptors at this case. DRD devices should not send OTG
> descriptors.
Agreed.
>
>> + udc->gadget->otg_caps = usb_otg_get_otg_caps(udc->gadget->otg_dev);
>
> Getting otg capabilities should be prior to driver->bind since
> usb_otg_descriptor_init is called at that. Besides, Gadget driver
Correct.
> may be probed before otg driver is registered
udc_bind_to_driver gets called only when both, udc driver and function driver
are available. Defer probing will have to be done in usb_add_gadget_udc_release().
>
> I am wonder if we can implement defer probe for gadget/udc/host driver
> if otg driver is not probed, in that case, some designs can be simpler
> like wait list in otg driver.
Agree with you on that. Should I work on implementing -EPROBE_DEFER for
hcd.c and udc-core.c if hcd/udc is meant for otg and OTG controller is not
yet probed?
--
cheers,
-roger
next prev parent reply other threads:[~2016-05-25 12:22 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-13 10:03 [PATCH v8 00/14] USB OTG/dual-role framework Roger Quadros
2016-05-13 10:03 ` [PATCH v8 01/14] usb: hcd: Initialize hcd->flags to 0 Roger Quadros
2016-05-13 10:03 ` [PATCH v8 02/14] usb: otg-fsm: Prevent build warning "VDBG" redefined Roger Quadros
2016-05-13 10:03 ` [PATCH v8 03/14] usb: hcd.h: Add OTG to HCD interface Roger Quadros
2016-05-13 10:03 ` [PATCH v8 04/14] usb: otg-fsm: use usb_otg wherever possible Roger Quadros
2016-05-13 10:03 ` [PATCH v8 05/14] usb: otg-fsm: move host controller operations into usb_otg->hcd_ops Roger Quadros
2016-05-13 10:03 ` [PATCH v8 06/14] usb: gadget.h: Add OTG to gadget interface Roger Quadros
2016-05-13 10:03 ` [PATCH v8 07/14] usb: otg: get rid of CONFIG_USB_OTG_FSM in favour of CONFIG_USB_OTG Roger Quadros
2016-05-13 10:03 ` [PATCH v8 08/14] usb: otg: add OTG/dual-role core Roger Quadros
2016-05-16 9:00 ` Roger Quadros
[not found] ` <CAL411-qb0dHQrn+AarSApCq6L=toKPRerLKDcx_H+5WDWu_VDg@mail.gmail.com>
2016-05-18 12:59 ` Roger Quadros
2016-05-20 8:31 ` Roger Quadros
2016-05-20 9:19 ` Roger Quadros
2016-05-20 9:53 ` Peter Chen
2016-05-23 10:06 ` Roger Quadros
2016-05-24 9:45 ` Roger Quadros
2016-05-25 2:44 ` Peter Chen
2016-05-25 3:19 ` Jun Li
2016-05-25 12:26 ` Roger Quadros
2016-05-25 12:21 ` Roger Quadros [this message]
2016-05-25 14:44 ` Jun Li
2016-05-13 10:03 ` [PATCH v8 09/14] usb: of: add an API to get OTG device from USB controller node Roger Quadros
2016-05-20 9:29 ` [PATCH v9 " Roger Quadros
2016-05-23 21:06 ` Rob Herring
2016-05-13 10:03 ` [PATCH v8 10/14] usb: otg: add hcd companion support Roger Quadros
2016-05-13 18:13 ` Rob Herring
2016-05-16 8:12 ` Roger Quadros
2016-05-20 9:32 ` [PATCH v9 " Roger Quadros
2016-05-23 21:07 ` Rob Herring
2016-05-13 10:03 ` [PATCH v8 11/14] usb: otg: use dev_dbg() instead of VDBG() Roger Quadros
2016-05-13 10:03 ` [PATCH v8 12/14] usb: hcd: Adapt to OTG core Roger Quadros
2016-05-13 10:03 ` [PATCH v8 13/14] usb: gadget: udc: adapt " Roger Quadros
2016-05-16 7:02 ` Peter Chen
2016-05-16 8:26 ` Roger Quadros
2016-05-16 9:23 ` Peter Chen
2016-05-16 9:51 ` Roger Quadros
2016-05-17 7:38 ` Jun Li
2016-05-17 8:08 ` Roger Quadros
2016-05-17 8:28 ` Jun Li
2016-05-18 12:42 ` Roger Quadros
2016-05-18 13:12 ` Jun Li
2016-05-18 13:43 ` Roger Quadros
2016-05-18 14:46 ` Jun Li
2016-05-19 7:32 ` Roger Quadros
2016-05-21 2:29 ` Peter Chen
2016-05-23 3:21 ` Peter Chen
2016-05-23 10:11 ` Roger Quadros
2016-05-23 10:34 ` Jun Li
2016-05-23 10:36 ` Roger Quadros
2016-05-24 2:53 ` Peter Chen
2016-06-08 7:32 ` Roger Quadros
2016-06-08 9:05 ` Peter Chen
2016-05-18 3:18 ` Peter Chen
2016-05-18 12:45 ` Roger Quadros
2016-05-20 1:39 ` Peter Chen
2016-05-20 7:26 ` Roger Quadros
2016-05-21 2:44 ` Peter Chen
2016-06-01 7:38 ` Peter Chen
2016-06-02 11:07 ` Roger Quadros
2016-05-13 10:03 ` [PATCH v8 14/14] usb: host: xhci-plat: Add otg device to platform data Roger Quadros
2016-05-30 9:29 ` [PATCH v8 00/14] USB OTG/dual-role framework Peter Chen
2016-05-30 14:04 ` Roger Quadros
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