[PATCH] usb: Ignore endpoints in non-zero altsettings

[Marek Vasut]

On 10/29/23 08:24, Hector Martin wrote:
> We currently do not really handle altsettings properly, and no driver
> uses them. Ignore the respective endpoint descriptors for secondary
> altsettings, to avoid creating duplicate endpoint records in the
> interface.
> 
> This will have to be revisited if/when we have a driver that needs
> altsettings to work properly.
> 
> Signed-off-by: Hector Martin <marcan at marcan.st>
> ---
>   common/usb.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/common/usb.c b/common/usb.c
> index aad13fd9c557..90f72fda00bc 100644
> --- a/common/usb.c
> +++ b/common/usb.c
> @@ -463,6 +463,15 @@ static int usb_parse_config(struct usb_device *dev,
>   				puts("Endpoint descriptor out of order!\n");
>   				break;
>   			}
> +			if (if_desc->num_altsetting > 1) {
> +				/*
> +				 * Ignore altsettings, which can trigger duplicate
> +				 * endpoint errors below. Revisit this when some
> +				 * driver actually needs altsettings with differing
> +				 * endpoint setups.
> +				 */

How do you trigger this error ?