On 22/01/2025 14:53, Greg KH wrote:
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> On Wed, Jan 22, 2025 at 02:47:32PM +0100, Catalin Popescu wrote:
>> A simple usb device has a single configuration and a single interface
>> and is considered as a "combined node" when defined in the devicetree.
>> If available, its interface node is simply ignored which is a problem
>> whenever the interface node has subnodes. To prevent that from happening
>> first check for any subnode and ignore the interface node only if no
>> subnode was found.
>>
>> Example: FTDI chip FT234XD that has only one UART interface which is
>> being used as a serdev by other driver.
>>
>> device@1 {
>> compatible = "usb403,6015";
>> reg = <1>;
>>
>> #address-cells = <2>;
>> #size-cells = <0>;
>>
>> interface@0 {
>> compatible = "usbif403,6015.config1.0";
>> reg = <0 1>;
>>
>> bluetooth {
>> compatible = "nxp,88w8987-bt";
>> };
>> };
>> };
> serdev can not use usb-serial devices due to the lack of hotplugging, so
> why is this an issue? I thought that just would not work.
Well, I can say that on 6.12.0 it's working :
[ 0.929493] usb 1-1: new full-speed USB device number 2 using xhci-hcd
[ 5.906574] usbcore: registered new interface driver ftdi_sio
[ 5.906632] usbserial: USB Serial support registered for FTDI USB
Serial Device
[ 5.906727] ftdi_sio 1-1:1.0: FTDI USB Serial Device converter detected
[ 5.906842] usb 1-1: Detected FT-X
[ 5.907809] serial serial0: tty port ttyUSB0 registered
[ 5.907832] usb 1-1: FTDI USB Serial Device converter now attached to
ttyUSB0
[ 5.918649] btnxpuart serial0-0: supply vcc not found, using dummy
regulator
==> unplug FTDI from USB bus
[ 109.410409] usb 1-1: USB disconnect, device number 2
[ 109.432556] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now
disconnected from ttyUSB0
[ 109.432634] ftdi_sio 1-1:1.0: device disconnected
==> plug back FTDI
[ 150.403378] usb 1-1: new full-speed USB device number 3 using xhci-hcd
[ 150.553794] ftdi_sio 1-1:1.0: FTDI USB Serial Device converter detected
[ 150.553920] usb 1-1: Detected FT-X
[ 150.554718] serial serial0: tty port ttyUSB0 registered
[ 150.554731] usb 1-1: FTDI USB Serial Device converter now attached to
ttyUSB0
[ 150.554976] btnxpuart serial0-0: supply vcc not found, using dummy
regulator
btnxpuart is basically the bluetooth driver that's behind the FTDI and
uses ttyUSB0 to communicate with the bluetooth chip.
I can confirm that after unplug/plug the communication with the
bluetooth chip is perfectly working.
BR,
Catalin
> confused,
>
> greg k-h
