Re: [PATCH v10 1/6] usb: gadget: udc: core: Introduce check_config to verify USB configuration

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 17, 2021 at 02:58:14AM -0700, Wesley Cheng wrote:
> Some UDCs may have constraints on how many high bandwidth endpoints it can
> support in a certain configuration.  This API allows for the composite
> driver to pass down the total number of endpoints to the UDC so it can verify
> it has the required resources to support the configuration.
> 
> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
> ---
>  drivers/usb/gadget/udc/core.c | 25 +++++++++++++++++++++++++
>  include/linux/usb/gadget.h    |  5 +++++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index b7f0b1e..e33ae2d 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1003,6 +1003,31 @@ int usb_gadget_ep_match_desc(struct usb_gadget *gadget,
>  }
>  EXPORT_SYMBOL_GPL(usb_gadget_ep_match_desc);
>  
> +/**
> + * usb_gadget_check_config - checks if the UDC can support the number of eps
> + * @gadget: controller to check the USB configuration
> + * @ep_map: bitmap of endpoints being requested by a USB configuration

Will a u64 really hold all of the possible endpoints?

Why make it odd like this, why not just provide a list like we do in the
USB core with the structure that USB drivers use?  What can a driver do
with a bitmap only?


thanks,

greg k-h