[PATCH 2/6] usb: xhci: Set up endpoints for the first 2 interfaces

[Marek Vasut]

On 2/27/24 8:38 AM, Janne Grunau wrote:
> Hej,
> 
> On Sun, Feb 25, 2024, at 22:47, Marek Vasut wrote:
>> On 2/25/24 4:28 PM, Janne Grunau wrote:
>>>
>>>
>>> On Wed, Feb 21, 2024, at 13:39, Marek Vasut wrote:
>>>> On 2/21/24 08:25, Janne Grunau via B4 Relay wrote:
>>>>> From: Janne Grunau <j at jannau.net>
>>>>>
>>>>> Apple USB keyboards carry the HID keyboard boot protocol on the second
>>>>> interface. Using the second interface in the USB keyboard driver does
>>>>> not work since the xhci has not allocated a transfer ring.
>>>>
>>>> So, what does this patch do ? That is not clear from the commit message.
>>>
>>> rewritten for v2:
>>> | usb: xhci: Set up endpoints for the first 2 interfaces
>>> |
>>> | The xhci driver currently only does the necessary initialization for
>>> | endpoints found in the first interface descriptor. Apple USB keyboards
>>> | (released 2021) use the second interface descriptor for the HID keyboard
>>> | boot protocol. To allow USB drivers to use endpoints from other
>>> | interface descriptors the xhci driver needs to ensure these endpoints
>>> | are initialized as well.
>>> | Use USB_MAX_ACTIVE_INTERFACES to control how many interface descriptors
>>> | are initialized and useable. Currently defined to 2 as that is enough to
>>> | make the Apple keyboard usable.
>>
>> Would it make sense to make this a tunable Kconfig option ?
> 
> I thought about that but I don't think it's worth it. We would have to default it to 2 (at least when the USB keyboard driver is enabled) since we can't predict which devices will be connected.
> Why would anyone chose a different value than the fixed value? I can't think of convincing reasons.

All right

Reviewed-by: Marek Vasut <marex at denx.de>