Re: [PATCH v2] usb: raw-gadget: fix gadget endpoint selection

[Felipe Balbi]

Hi,

Andrey Konovalov <andreyknvl@xxxxxxxxxx> writes:

> Currently automatic gadget endpoint selection based on required features
> doesn't work. Raw Gadget tries iterating over the list of available
> endpoints and finding one that has the right direction and transfer type.
> Unfortunately selecting arbitrary gadget endpoints (even if they satisfy
> feature requirements) doesn't work, as (depending on the UDC driver) they
> might have fixed addresses, and one also needs to provide matching
> endpoint addresses in the descriptors sent to the host.
>
> The composite framework deals with this by assigning endpoint addresses
> in usb_ep_autoconfig() before enumeration starts. This approach won't work
> with Raw Gadget as the endpoints are supposed to be enabled after a
> set_configuration/set_interface request from the host, so it's too late to
> patch the endpoint descriptors that had already been sent to the host.
>
> For Raw Gadget we take another approach. Similarly to GadgetFS, we allow
> the user to make the decision as to which gadget endpoints to use.
>
> This patch adds another Raw Gadget ioctl USB_RAW_IOCTL_EPS_INFO that
> exposes information about all non-control endpoints that a currently
> connected UDC has. This information includes endpoints addresses, as well
> as their capabilities and limits to allow the user to choose the most
> fitting gadget endpoint.
>
> The USB_RAW_IOCTL_EP_ENABLE ioctl is updated to use the proper endpoint
> validation routine usb_gadget_ep_match_desc() and also now accepts an
> optional usb_ss_ep_comp_descriptor argument.
>
> These changes affect the portability of the gadgets that use Raw Gadget
> when running on different UDCs. Nevertheless, as long as the user relies
> on the information provided by USB_RAW_IOCTL_EPS_INFO to dynamically
> choose endpoint addresses, UDC-agnostic gadgets can still be written with
> Raw Gadget.
>
> Fixes: f2c2e717642c ("usb: gadget: add raw-gadget interface")
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> ---
>
> Changes v1 -> v2:
> - Validate endpoint number against dev->eps_num instead of
>   USB_RAW_EPS_NUM_MAX.
> - Dropped maxburst from struct usb_raw_ep_limits, added reserved field
>   instead.
> - Don't allocate struct usb_raw_eps_info on stack, it's too large.
> - Assign SuperSpeed endpoint companion descriptor to usb_ep when enabling
>   endpoints.
> - Fixed typos in commit message.
>
> ---
>  Documentation/usb/raw-gadget.rst       |   6 +-
>  drivers/usb/gadget/legacy/raw_gadget.c | 217 +++++++++++++++++--------
>  include/uapi/linux/usb/raw_gadget.h    |  88 +++++++++-
>  3 files changed, 231 insertions(+), 80 deletions(-)
>
> diff --git a/Documentation/usb/raw-gadget.rst b/Documentation/usb/raw-gadget.rst
> index 9e78cb858f86..42bd446d72b2 100644
> --- a/Documentation/usb/raw-gadget.rst
> +++ b/Documentation/usb/raw-gadget.rst
> @@ -27,11 +27,7 @@ differences are:
>  3. Raw Gadget provides a way to select a UDC device/driver to bind to,
>     while GadgetFS currently binds to the first available UDC.
>  
> -4. Raw Gadget uses predictable endpoint names (handles) across different
> -   UDCs (as long as UDCs have enough endpoints of each required transfer
> -   type).
> -
> -5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
> +4. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
>  
>  Userspace interface
>  ~~~~~~~~~~~~~~~~~~~
> diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c
> index 7b241992ad5a..e6abbc15341a 100644
> --- a/drivers/usb/gadget/legacy/raw_gadget.c
> +++ b/drivers/usb/gadget/legacy/raw_gadget.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/compiler.h>
> +#include <linux/ctype.h>
>  #include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/kref.h>
> @@ -123,8 +124,6 @@ static void raw_event_queue_destroy(struct raw_event_queue *queue)
>  
>  struct raw_dev;
>  
> -#define USB_RAW_MAX_ENDPOINTS 32
> -
>  enum ep_state {
>  	STATE_EP_DISABLED,
>  	STATE_EP_ENABLED,
> @@ -134,6 +133,7 @@ struct raw_ep {
>  	struct raw_dev		*dev;
>  	enum ep_state		state;
>  	struct usb_ep		*ep;
> +	u8			addr;
>  	struct usb_request	*req;
>  	bool			urb_queued;
>  	bool			disabling;
> @@ -168,7 +168,8 @@ struct raw_dev {
>  	bool				ep0_out_pending;
>  	bool				ep0_urb_queued;
>  	ssize_t				ep0_status;
> -	struct raw_ep			eps[USB_RAW_MAX_ENDPOINTS];
> +	struct raw_ep			eps[USB_RAW_EPS_NUM_MAX];
> +	int				eps_num;
>  
>  	struct completion		ep0_done;
>  	struct raw_event_queue		queue;
> @@ -202,7 +203,7 @@ static void dev_free(struct kref *kref)
>  		usb_ep_free_request(dev->gadget->ep0, dev->req);
>  	}
>  	raw_event_queue_destroy(&dev->queue);
> -	for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
> +	for (i = 0; i < dev->eps_num; i++) {
>  		if (dev->eps[i].state != STATE_EP_ENABLED)
>  			continue;
>  		usb_ep_disable(dev->eps[i].ep);
> @@ -249,12 +250,26 @@ static void gadget_ep0_complete(struct usb_ep *ep, struct usb_request *req)
>  	complete(&dev->ep0_done);
>  }
>  
> +static u8 get_ep_addr(const char *name)
> +{
> +	/* If the endpoint has fixed function (named as e.g. "ep12out-bulk"),
> +	 * parse the endpoint address from its name. We deliberately use
> +	 * deprecated simple_strtoul() function here, as the number isn't
> +	 * followed by '\0' nor '\n'.
> +	 */
> +	if (isdigit(name[2]))
> +		return simple_strtoul(&name[2], NULL, 10);
> +	/* Otherwise the endpoint is configurable (named as e.g. "ep-a"). */
> +	return USB_RAW_EP_ADDR_ANY;
> +}
> +
>  static int gadget_bind(struct usb_gadget *gadget,
>  			struct usb_gadget_driver *driver)
>  {
> -	int ret = 0;
> +	int ret = 0, i = 0;
>  	struct raw_dev *dev = container_of(driver, struct raw_dev, driver);
>  	struct usb_request *req;
> +	struct usb_ep *ep;
>  	unsigned long flags;
>  
>  	if (strcmp(gadget->name, dev->udc_name) != 0)
> @@ -273,6 +288,13 @@ static int gadget_bind(struct usb_gadget *gadget,
>  	dev->req->context = dev;
>  	dev->req->complete = gadget_ep0_complete;
>  	dev->gadget = gadget;
> +	gadget_for_each_ep(ep, dev->gadget) {
> +		dev->eps[i].ep = ep;
> +		dev->eps[i].addr = get_ep_addr(ep->name);
> +		dev->eps[i].state = STATE_EP_DISABLED;
> +		i++;
> +	}
> +	dev->eps_num = i;
>  	spin_unlock_irqrestore(&dev->lock, flags);
>  
>  	/* Matches kref_put() in gadget_unbind(). */
> @@ -555,7 +577,7 @@ static void *raw_alloc_io_data(struct usb_raw_ep_io *io, void __user *ptr,
>  
>  	if (copy_from_user(io, ptr, sizeof(*io)))
>  		return ERR_PTR(-EFAULT);
> -	if (io->ep >= USB_RAW_MAX_ENDPOINTS)
> +	if (io->ep >= USB_RAW_EPS_NUM_MAX)
>  		return ERR_PTR(-EINVAL);
>  	if (!usb_raw_io_flags_valid(io->flags))
>  		return ERR_PTR(-EINVAL);
> @@ -682,52 +704,34 @@ static int raw_ioctl_ep0_read(struct raw_dev *dev, unsigned long value)
>  	return ret;
>  }
>  
> -static bool check_ep_caps(struct usb_ep *ep,
> -				struct usb_endpoint_descriptor *desc)
> -{
> -	switch (usb_endpoint_type(desc)) {
> -	case USB_ENDPOINT_XFER_ISOC:
> -		if (!ep->caps.type_iso)
> -			return false;
> -		break;
> -	case USB_ENDPOINT_XFER_BULK:
> -		if (!ep->caps.type_bulk)
> -			return false;
> -		break;
> -	case USB_ENDPOINT_XFER_INT:
> -		if (!ep->caps.type_int)
> -			return false;
> -		break;
> -	default:
> -		return false;
> -	}
> -
> -	if (usb_endpoint_dir_in(desc) && !ep->caps.dir_in)
> -		return false;
> -	if (usb_endpoint_dir_out(desc) && !ep->caps.dir_out)
> -		return false;
> -
> -	return true;
> -}
> -
>  static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
>  {
>  	int ret = 0, i;
>  	unsigned long flags;
> -	struct usb_endpoint_descriptor *desc;
> -	struct usb_ep *ep = NULL;
> +	struct usb_raw_ep_descs *descs;
> +	struct usb_endpoint_descriptor *ep_desc;
> +	struct usb_ss_ep_comp_descriptor *comp_desc = NULL;
> +	struct raw_ep *ep;
>  
> -	desc = memdup_user((void __user *)value, sizeof(*desc));
> -	if (IS_ERR(desc))
> -		return PTR_ERR(desc);
> +	descs = memdup_user((void __user *)value, sizeof(*descs));
> +	if (IS_ERR(descs))
> +		return PTR_ERR(descs);
> +
> +	ep_desc = &descs->ep;
> +	/*
> +	 * Assume that SuperSpeed endpoint companion descriptor is not present
> +	 * if its length is 0.
> +	 */
> +	if (descs->comp.bLength != 0)
> +		comp_desc = &descs->comp;
>  
>  	/*
>  	 * Endpoints with a maxpacket length of 0 can cause crashes in UDC
>  	 * drivers.
>  	 */
> -	if (usb_endpoint_maxp(desc) == 0) {
> +	if (usb_endpoint_maxp(ep_desc) == 0) {
>  		dev_dbg(dev->dev, "fail, bad endpoint maxpacket\n");
> -		kfree(desc);
> +		kfree(descs);
>  		return -EINVAL;
>  	}
>  
> @@ -743,41 +747,34 @@ static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
>  		goto out_free;
>  	}
>  
> -	for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
> -		if (dev->eps[i].state == STATE_EP_ENABLED)
> +	for (i = 0; i < dev->eps_num; i++) {
> +		ep = &dev->eps[i];
> +		if (ep->state != STATE_EP_DISABLED)
>  			continue;
> -		break;
> -	}
> -	if (i == USB_RAW_MAX_ENDPOINTS) {
> -		dev_dbg(&dev->gadget->dev,
> -				"fail, no device endpoints available\n");
> -		ret = -EBUSY;
> -		goto out_free;
> -	}
> -
> -	gadget_for_each_ep(ep, dev->gadget) {
> -		if (ep->enabled)
> +		if (ep->addr != usb_endpoint_num(ep_desc) &&
> +				ep->addr != USB_RAW_EP_ADDR_ANY)
>  			continue;
> -		if (!check_ep_caps(ep, desc))
> +		if (!usb_gadget_ep_match_desc(dev->gadget, ep->ep,
> +							ep_desc, comp_desc))
>  			continue;
> -		ep->desc = desc;
> -		ret = usb_ep_enable(ep);
> +		ep->ep->desc = ep_desc;
> +		ep->ep->comp_desc = comp_desc;
> +		ret = usb_ep_enable(ep->ep);
>  		if (ret < 0) {
>  			dev_err(&dev->gadget->dev,
>  				"fail, usb_ep_enable returned %d\n", ret);
>  			goto out_free;
>  		}
> -		dev->eps[i].req = usb_ep_alloc_request(ep, GFP_ATOMIC);
> -		if (!dev->eps[i].req) {
> +		ep->req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC);
> +		if (!ep->req) {
>  			dev_err(&dev->gadget->dev,
>  				"fail, usb_ep_alloc_request failed\n");
> -			usb_ep_disable(ep);
> +			usb_ep_disable(ep->ep);
>  			ret = -ENOMEM;
>  			goto out_free;
>  		}
> -		dev->eps[i].ep = ep;
> -		dev->eps[i].state = STATE_EP_ENABLED;
> -		ep->driver_data = &dev->eps[i];
> +		ep->state = STATE_EP_ENABLED;
> +		ep->ep->driver_data = ep;
>  		ret = i;
>  		goto out_unlock;
>  	}
> @@ -786,7 +783,7 @@ static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
>  	ret = -EBUSY;
>  
>  out_free:
> -	kfree(desc);
> +	kfree(descs);
>  out_unlock:
>  	spin_unlock_irqrestore(&dev->lock, flags);
>  	return ret;
> @@ -796,10 +793,6 @@ static int raw_ioctl_ep_disable(struct raw_dev *dev, unsigned long value)
>  {
>  	int ret = 0, i = value;
>  	unsigned long flags;
> -	const void *desc;
> -
> -	if (i < 0 || i >= USB_RAW_MAX_ENDPOINTS)
> -		return -EINVAL;
>  
>  	spin_lock_irqsave(&dev->lock, flags);
>  	if (dev->state != STATE_DEV_RUNNING) {
> @@ -812,6 +805,11 @@ static int raw_ioctl_ep_disable(struct raw_dev *dev, unsigned long value)
>  		ret = -EBUSY;
>  		goto out_unlock;
>  	}
> +	if (i < 0 || i >= dev->eps_num) {
> +		dev_dbg(dev->dev, "fail, invalid endpoint\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
>  	if (dev->eps[i].state != STATE_EP_ENABLED) {
>  		dev_dbg(&dev->gadget->dev, "fail, endpoint is not enabled\n");
>  		ret = -EINVAL;
> @@ -836,10 +834,13 @@ static int raw_ioctl_ep_disable(struct raw_dev *dev, unsigned long value)
>  
>  	spin_lock_irqsave(&dev->lock, flags);
>  	usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
> -	desc = dev->eps[i].ep->desc;
> +	/*
> +	 * This kfree() frees both endpoint and SuperSpeed
> +	 * endpoint companion descriptors.
> +	 */
> +	kfree(dev->eps[i].ep->desc);
>  	dev->eps[i].ep = NULL;
>  	dev->eps[i].state = STATE_EP_DISABLED;
> -	kfree(desc);
>  	dev->eps[i].disabling = false;
>  
>  out_unlock:
> @@ -868,7 +869,7 @@ static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
>  {
>  	int ret = 0;
>  	unsigned long flags;
> -	struct raw_ep *ep = &dev->eps[io->ep];
> +	struct raw_ep *ep;
>  	DECLARE_COMPLETION_ONSTACK(done);
>  
>  	spin_lock_irqsave(&dev->lock, flags);
> @@ -882,6 +883,12 @@ static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
>  		ret = -EBUSY;
>  		goto out_unlock;
>  	}
> +	if (io->ep >= dev->eps_num) {
> +		dev_dbg(&dev->gadget->dev, "fail, invalid endpoint\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	ep = &dev->eps[io->ep];
>  	if (ep->state != STATE_EP_ENABLED) {
>  		dev_dbg(&dev->gadget->dev, "fail, endpoint is not enabled\n");
>  		ret = -EBUSY;
> @@ -1027,6 +1034,71 @@ static int raw_ioctl_vbus_draw(struct raw_dev *dev, unsigned long value)
>  	return ret;
>  }
>  
> +static void fill_ep_caps(struct usb_ep_caps *caps,
> +				struct usb_raw_ep_caps *raw_caps)
> +{
> +	raw_caps->type_control = caps->type_control;
> +	raw_caps->type_iso = caps->type_iso;
> +	raw_caps->type_bulk = caps->type_bulk;
> +	raw_caps->type_int = caps->type_int;
> +	raw_caps->dir_in = caps->dir_in;
> +	raw_caps->dir_out = caps->dir_out;
> +}
> +
> +static void fill_ep_limits(struct usb_ep *ep, struct usb_raw_ep_limits *limits)
> +{
> +	limits->maxpacket_limit = ep->maxpacket_limit;
> +	limits->max_streams = ep->max_streams;
> +}
> +
> +static int raw_ioctl_eps_info(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0, i;
> +	unsigned long flags;
> +	struct usb_raw_eps_info *info;
> +	struct raw_ep *ep;
> +
> +	info = kmalloc(sizeof(*info), GFP_KERNEL);
> +	if (!info) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		dev_dbg(dev->dev, "fail, device is not running\n");
> +		ret = -EINVAL;
> +		spin_unlock_irqrestore(&dev->lock, flags);
> +		goto out_free;
> +	}
> +	if (!dev->gadget) {
> +		dev_dbg(dev->dev, "fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		spin_unlock_irqrestore(&dev->lock, flags);
> +		goto out_free;
> +	}
> +
> +	memset(info, 0, sizeof(*info));
> +	for (i = 0; i < dev->eps_num; i++) {
> +		ep = &dev->eps[i];
> +		strscpy(&info->eps[i].name[0], ep->ep->name,
> +				USB_RAW_EP_NAME_MAX);
> +		info->eps[i].addr = ep->addr;
> +		fill_ep_caps(&ep->ep->caps, &info->eps[i].caps);
> +		fill_ep_limits(ep->ep, &info->eps[i].limits);
> +	}
> +	ret = dev->eps_num;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	if (copy_to_user((void __user *)value, info, sizeof(*info)))
> +		ret = -EFAULT;
> +
> +out_free:
> +	kfree(info);
> +out:
> +	return ret;
> +}
> +
>  static long raw_ioctl(struct file *fd, unsigned int cmd, unsigned long value)
>  {
>  	struct raw_dev *dev = fd->private_data;
> @@ -1069,6 +1141,9 @@ static long raw_ioctl(struct file *fd, unsigned int cmd, unsigned long value)
>  	case USB_RAW_IOCTL_VBUS_DRAW:
>  		ret = raw_ioctl_vbus_draw(dev, value);
>  		break;
> +	case USB_RAW_IOCTL_EPS_INFO:
> +		ret = raw_ioctl_eps_info(dev, value);
> +		break;
>  	default:
>  		ret = -EINVAL;
>  	}
> diff --git a/include/uapi/linux/usb/raw_gadget.h b/include/uapi/linux/usb/raw_gadget.h
> index 8544802b25bd..722124fff290 100644
> --- a/include/uapi/linux/usb/raw_gadget.h
> +++ b/include/uapi/linux/usb/raw_gadget.h
> @@ -93,6 +93,79 @@ struct usb_raw_ep_io {
>  	__u8		data[0];
>  };
>  
> +/*
> + * struct usb_raw_ep_descs - argument for USB_RAW_IOCTL_EP_ENABLE ioctl.
> + * @ep: Endpoint descriptor.
> + * @comp: SuperSpeed Endpoint Companion descriptor.
> + *
> + * Both of these descriptors are only used by the gadget subsystem including
> + * the UDC driver and don't affect the descriptors that are sent to the host.
> + * However, the user must make sure that the host and the gadget sides agree
> + * on the used endpoint parameters (such as e.g. endpoint addresses).
> + */
> +struct usb_raw_ep_descs {
> +	struct usb_endpoint_descriptor		ep;
> +	struct usb_ss_ep_comp_descriptor	comp;
> +};
> +
> +/* Maximum number of non-control endpoints in struct usb_raw_eps_info. */
> +#define USB_RAW_EPS_NUM_MAX	30
> +
> +/* Maximum length of UDC endpoint name in struct usb_raw_ep_info. */
> +#define USB_RAW_EP_NAME_MAX	16
> +
> +/* Used as addr in struct usb_raw_ep_info if endpoint accepts any address. */
> +#define USB_RAW_EP_ADDR_ANY	0xff
> +
> +/*
> + * struct usb_raw_ep_caps - exposes endpoint capabilities from struct usb_ep
> + *     (technically from its member struct usb_ep_caps).
> + */
> +struct usb_raw_ep_caps {
> +	__u32	type_control	: 1;
> +	__u32	type_iso	: 1;
> +	__u32	type_bulk	: 1;
> +	__u32	type_int	: 1;
> +	__u32	dir_in		: 1;
> +	__u32	dir_out		: 1;
> +};
> +
> +/*
> + * struct usb_raw_ep_limits - exposes endpoint limits from struct usb_ep.
> + * @maxpacket_limit: Maximum packet size value supported by this endpoint.
> + * @max_streams: maximum number of streams supported by this endpoint
> + *     (actual number is 2^n).
> + * @reserved: Empty, reserved for potential future extensions.
> + */
> +struct usb_raw_ep_limits {
> +	__u16	maxpacket_limit;
> +	__u16	max_streams;
> +	__u32	reserved;
> +};
> +
> +/*
> + * struct usb_raw_ep_info - stores information about a gadget endpoint.
> + * @name: Name of the endpoint as it is defined in the UDC driver.
> + * @addr: Address of the endpoint that must be specified in the endpoint
> + *     descriptor passed to USB_RAW_IOCTL_EP_ENABLE ioctl.
> + * @caps: Endpoint capabilities.
> + * @limits: Endpoint limits.
> + */
> +struct usb_raw_ep_info {
> +	__u8				name[USB_RAW_EP_NAME_MAX];
> +	__u32				addr;
> +	struct usb_raw_ep_caps		caps;
> +	struct usb_raw_ep_limits	limits;
> +};
> +
> +/*
> + * struct usb_raw_eps_info - argument for USB_RAW_IOCTL_EPS_INFO ioctl.
> + * eps: Structures that store information about non-control endpoints.
> + */
> +struct usb_raw_eps_info {
> +	struct usb_raw_ep_info	eps[USB_RAW_EPS_NUM_MAX];
> +};
> +
>  /*
>   * Initializes a Raw Gadget instance.
>   * Accepts a pointer to the usb_raw_init struct as an argument.
> @@ -126,12 +199,12 @@ struct usb_raw_ep_io {
>  #define USB_RAW_IOCTL_EP0_READ		_IOWR('U', 4, struct usb_raw_ep_io)
>  
>  /*
> - * Finds an endpoint that supports the transfer type specified in the
> - * descriptor and enables it.
> - * Accepts a pointer to the usb_endpoint_descriptor struct as an argument.
> + * Finds an endpoint that satisfies the parameters specified in the provided
> + * descriptors (address, transfer type, etc.) and enables it.
> + * Accepts a pointer to the usb_raw_ep_descs struct as an argument.
>   * Returns enabled endpoint handle on success or negative error code on failure.
>   */
> -#define USB_RAW_IOCTL_EP_ENABLE		_IOW('U', 5, struct usb_endpoint_descriptor)
> +#define USB_RAW_IOCTL_EP_ENABLE		_IOW('U', 5, struct usb_raw_ep_descs)
>  
>  /* Disables specified endpoint.
>   * Accepts endpoint handle as an argument.
> @@ -164,4 +237,11 @@ struct usb_raw_ep_io {
>   */
>  #define USB_RAW_IOCTL_VBUS_DRAW		_IOW('U', 10, __u32)
>  
> +/* Fills in the usb_raw_eps_info structure with information about non-control
> + * endpoints available for the currently connected UDC.
> + * Returns the number of available endpoints on success or negative error code
> + * on failure.
> + */
> +#define USB_RAW_IOCTL_EPS_INFO		_IOR('U', 11, struct usb_raw_eps_info)
> +

here you're changing userspace ABI. Aren't we going to possibly break
some existing applications?

-- 
balbi

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