On Tue, Sep 17, 2024 at 06:49:48AM +0200, Marco Felsch wrote: > On 24-09-09, Johan Hovold wrote: > > On Wed, Aug 07, 2024 at 04:08:47PM +0200, Marco Felsch wrote: > > > this patchset is based on Johan's patches [1] but dropped the need of > > > the special 'serial' of-node [2]. > > > > That's great that you found and referenced my proof-of-concept patches, > > but it doesn't seem like you tried to understand why this hasn't been > > merged yet. > > First, as the commit message you refer to below explain, we need some > > way to describe multiport controllers. Just dropping the 'serial' node > > does not make that issue go away. > > Sorry for asking but isn't the current OF abstraction [1] enough? As far > as I understood we can describe the whole USB tree within OF. I used [1] > and the this patchset to describe the following hierarchy: > > usb-root -> usb-hub port-1 -> usb-serial interface-0 -> serial > bt-module > > [1] Documentation/devicetree/bindings/usb/usb-device.yaml Again, you still need to consider devices with multiple serial ports (and they do not always map neatly to one port per interface either). > > Second, and more importantly, you do not address the main obstacle for > > enabling serdev for USB serial which is that the serdev cannot handle > > hotplugging. > > Hotplugging is a good point but out-of-scope IMHO (at least for now) > since the current serdev implementation rely on additional firmware > information e.g OF node to be present. E.g. if the above mentioned setup > would connect the "serial bt-module" directly to the UART port you still > need an OF node to bind the serdev driver. If the node isn't present > user-space would need to do the hci handling. There's nothing preventing you from adding a devicetree node for a USB device that can be unplugged. > So from my POV the serdev abstraction is for manufacturers which make > use of "onboard" usb-devices which are always present at the same USB > tree location. Serdev is not made for general purpose USB ports (yet) > where a user can plug-in all types of USB devices. Right, but someone need to make sure that serdev can handle devices going away first as nothing is currently preventing that from happening. > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial.git/log/?h=usb-serial-of > > > [2] https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial.git/commit/?h=usb-serial-of&id=b19239022c92567a6a9ed40e8522e84972b0997f Johan
