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

[Hector Martin]

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 <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 ?
> 

Plug in a device with altsettings, like most sound cards or UVC devices.

- Hector