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@xxxxxx>
> ---
> 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.
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;
+ udc->gadget->otg_caps = usb_otg_get_otg_caps(udc->gadget->otg_dev);
mutex_unlock(&udc_lock);
usb_otg_register_gadget(udc->gadget, &otg_gadget_intf);
mutex_lock(&udc_lock);
} else {
ret = usb_gadget_udc_start(udc);
if (ret) {
driver->unbind(udc->gadget);
goto err1;
}
usb_udc_connect_control(udc);
}
..
}
What do you say?
regards,
-roger
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