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

[Andrey Konovalov]

On Tue, May 5, 2020 at 9:34 AM Felipe Balbi <balbi@xxxxxxxxxx> wrote:
>
>
> 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?

Hi Felipe,

 I've been working on tests for Raw Gadget for the last few weeks [1],
which revealed a few problems with the interface. This isn't yet
included into any released kernel, so my hope that changing the ABI is
OK during the rc stage.

[1] https://github.com/xairy/raw-gadget/tree/tests

Thanks!