On Thu, 2023-02-09 at 13:32 -0800, Luiz Augusto von Dentz wrote: > On Tue, Feb 7, 2023 at 3:58 AM Tomasz Moń <tomasz.mon@xxxxxxxxxxxxx> wrote: > > Remove hardcoded interface number check because Bluetooth specification > > since version 4.0 only recommends and no longer requires specific > > interface numbers. > > > > While earlier Bluetooth versions, i.e. 2.1 + EDR and 3.0 + HS, contain > > required configuration table in Volume 4 - Host Controller Interface > > Part B - USB Transport Layer, Bluetooth Core Specification Addendum 2 > > changes the table from required to recommended configuration. > > Can you give it a little more context, is this supposed to be the case > for LE only controllers? I assume this shouldn't cause any regressions > for other controllers right? Why do you think it is the case for LE only controllers? The Bluetooth Host Controller interface is not limited to LE. I believe this doesn't cause any regressions for other controllers. Because I don't know anything nor have access to the Apple-specific (Broadcom) devices that have BTUSB_IFNUM_2 flag set, I left the BTUSB_IFNUM_2 check intact. It might be that the BTUSB_IFNUM_2 is not necessary after all (and was only added because of this no longer necessary hardcoded interface check), but you really need the actual hardware to tell. Note that this patch is merely removing the no longer necessary check and otherwise leaving the communication intact. The hardcoded interface check is preventing btusb from attaching to Bluetooth HCI controller in a composite device that have some other interface under the number 0. The composite devices that previously failed due to check do work with this patch, because the specification (Bluetooth Core Specification Version 5.3 Vol 4, Part B 2.2.2 Controller function in a composite device) says host **should** address control packets to Interface (and not Device) while at the same time the specification explicitly says that the device **shall** recognize the HCI command packets directed to Device. Because **should** equals to recommended and **shall** is mandatory requirement, the btusb driver is actually compliant even if it always directs the control transfers to Device. -- Tomasz Moń | Senior Firmware Engineer P +48 882 826 111 | Wrocław, Poland nordicsemi.com | devzone.nordicsemi.com
