On 29/10/2023 21.04, Marek Vasut wrote:
> 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 <mar...@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 ?
>
Plug in a device with altsettings, like most sound cards or UVC devices.
- Hector
