Re: [PATCH v6 09/12] usb: gadget: udc: adapt to OTG core

[Roger Quadros]

On 18/04/16 09:59, Peter Chen wrote:
> On Tue, Apr 05, 2016 at 05:05:14PM +0300, Roger Quadros wrote:
>> The OTG state machine needs a mechanism to start and
>> stop the gadget controller. Add usb_gadget_start()
>> and usb_gadget_stop().
>>
>> Introduce usb_otg_add_gadget_udc() to allow controller drivers
>> to register a gadget controller that is part of an OTG instance.
>>
>> Register with OTG core when gadget function driver
>> is available and unregister when function driver is unbound.
>>
>> We need to unlock the usb_lock mutexbefore calling
> 
> ...mutex before...

OK.
> 
>> usb_otg_register_gadget() in udc_bind_to_driver() and
>> usb_gadget_remove_driver() else it will cause a circular
>> locking dependency.
>>
>> Ignore softconnect sysfs control when we're in OTG
>> mode as OTG FSM takes care of gadget softconnect using
>> the b_bus_req mechanism.
>>
>> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
>> ---
>>  drivers/usb/gadget/udc/udc-core.c | 166 +++++++++++++++++++++++++++++++++++---
>>  include/linux/usb/gadget.h        |   4 +
>>  2 files changed, 161 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
>> index 4151597..9b9702f 100644
>> --- a/drivers/usb/gadget/udc/udc-core.c
>> +++ b/drivers/usb/gadget/udc/udc-core.c
>> @@ -28,6 +28,10 @@
>>  #include <linux/usb/ch9.h>
>>  #include <linux/usb/gadget.h>
>>  #include <linux/usb.h>
>> +#include <linux/usb/otg.h>
>> +
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>>  
>>  /**
>>   * struct usb_udc - describes one usb device controller
>> @@ -304,6 +308,7 @@ EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);
>>   */
>>  static inline int usb_gadget_udc_start(struct usb_udc *udc)
>>  {
>> +	dev_dbg(&udc->dev, "%s\n", __func__);
>>  	return udc->gadget->ops->udc_start(udc->gadget, udc->driver);
>>  }
> 
> You may delete the debug message next time.

OK for this and all the next comments to remove debug messages.

> 
>>  
>> @@ -321,10 +326,81 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc)
>>   */
>>  static inline void usb_gadget_udc_stop(struct usb_udc *udc)
>>  {
>> +	dev_dbg(&udc->dev, "%s\n", __func__);
>>  	udc->gadget->ops->udc_stop(udc->gadget);
>>  }
> 
> The same.
> 
>>  
>>  /**
>> + * usb_gadget_start - start the usb gadget controller and connect to bus
>> + * @gadget: the gadget device to start
>> + *
>> + * This is external API for use by OTG core.
>> + *
>> + * Start the usb device controller and connect to bus (enable pull).
>> + */
>> +static int usb_gadget_start(struct usb_gadget *gadget)
>> +{
>> +	int ret;
>> +	struct usb_udc *udc = NULL;
>> +
>> +	dev_dbg(&gadget->dev, "%s\n", __func__);
> 
> The same
> 
>> +	mutex_lock(&udc_lock);
>> +	list_for_each_entry(udc, &udc_list, list)
>> +		if (udc->gadget == gadget)
>> +			goto found;
>> +
>> +	dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
>> +		__func__);
>> +	mutex_unlock(&udc_lock);
>> +	return -EINVAL;
>> +
>> +found:
>> +	ret = usb_gadget_udc_start(udc);
>> +	if (ret)
>> +		dev_err(&udc->dev, "USB Device Controller didn't start: %d\n",
>> +			ret);
>> +	else
>> +		usb_udc_connect_control(udc);
>> +
>> +	mutex_unlock(&udc_lock);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * usb_gadget_stop - disconnect from bus and stop the usb gadget
>> + * @gadget: The gadget device we want to stop
>> + *
>> + * This is external API for use by OTG core.
>> + *
>> + * Disconnect from the bus (disable pull) and stop the
>> + * gadget controller.
>> + */
>> +static int usb_gadget_stop(struct usb_gadget *gadget)
>> +{
>> +	struct usb_udc *udc = NULL;
>> +
>> +	dev_dbg(&gadget->dev, "%s\n", __func__);
> 
> The same
> 	
>> +	mutex_lock(&udc_lock);
>> +	list_for_each_entry(udc, &udc_list, list)
>> +		if (udc->gadget == gadget)
>> +			goto found;
>> +
>> +	dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
>> +		__func__);
>> +	mutex_unlock(&udc_lock);
>> +	return -EINVAL;
> 
> The above finding gadget code is the same with usb_gadget_start, can we
> use one common API to instead of it?

Sure.
> 
>> +
>> +found:
>> +	usb_gadget_disconnect(udc->gadget);
>> +	udc->driver->disconnect(udc->gadget);
>> +	usb_gadget_udc_stop(udc);
>> +	mutex_unlock(&udc_lock);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>>   * usb_udc_release - release the usb_udc struct
>>   * @dev: the dev member within usb_udc
>>   *
>> @@ -486,6 +562,48 @@ int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget)
>>  }
>>  EXPORT_SYMBOL_GPL(usb_add_gadget_udc);
>>  
>> +/**
>> + * usb_otg_add_gadget_udc - adds a new gadget to the udc class driver list
>> + * @parent: the parent device to this udc. Usually the controller
>> + * driver's device.
>> + * @gadget: the gadget to be added to the list
>> + * @otg_dev: the OTG controller device
>> + *
>> + * If otg_dev is NULL then device tree node is checked
>> + * for OTG controller via the otg-controller property.
>> + * Returns zero on success, negative errno otherwise.
>> + */
>> +int usb_otg_add_gadget_udc(struct device *parent, struct usb_gadget *gadget,
>> +			   struct device *otg_dev)
>> +{
>> +	if (!otg_dev) {
>> +		struct device_node *np;
>> +		struct platform_device *pdev;
>> +
>> +		np = of_parse_phandle(parent->of_node, "otg-controller", 0);
>> +		if (!np) {
>> +			dev_err(parent,
>> +				"otg_dev is NULL or no otg-controller property in DT\n");
>> +			return -EINVAL;
>> +		}
>> +
>> +		pdev = of_find_device_by_node(np);
>> +		of_node_put(np);
>> +		if (!pdev) {
>> +			dev_err(parent, "couldn't get otg-controller device\n");
>> +			return -ENODEV;
>> +		}
>> +
>> +		gadget->otg_dev = &pdev->dev;
>> +	} else {
>> +		gadget->otg_dev = otg_dev;
>> +	}
> 
> The above the code is duplicated with hcd's. Can we do something common
> at usb-otg.c, eg define an API get_usb_otg_dev(struct usb_gadget *gadget, struct
> usb_hcd *hcd), in this API we can try to get otg_dev for both gadget and
> hcd, and we can call it at controller driver during register otg.
> 
Good point. I'll address it in v7.

cheers,
-roger