[PATCH v4 1/4] cmd: bind: Add unbind command with driver filter

[Marek Vasut]

On 8/4/23 19:01, Miquel Raynal wrote:
> Hi Tom,
> 
>>>>>>> Well, what's needed / is it possible to get to the point where we don't
>>>>>>> _need_ to call bind/unbind for each of these cases? Is there something
>>>>>>> we're supposed to be setting in the DT that we aren't?
>>>>>>
>>>>>> You do need to unbind the ethernet before using fastboot, always, with the 'unbind ethernet 0', you dont need the peripheral unbind/rebind part, so it should behave like before.
>>>>>
>>>>> And for my own understanding, why don't we need to bind a fastboot
>>>>> gadget?
>>>>
>>>> The fastboot command does that internally .
>>>
>>> This is not visible with dm tree and I did not find how to bind the
>>> fastboot gadget manually.
>>>
>>> This makes the CLI clearly uneven and the internal code badly different
>>> between gadgets/commands. Why can't we have them both
>>> autoloaded/unloaded like before? I think I missed something which
>>> explains the rationale behind this series.
>>
>> They aren't both auto-loaded currently. We have a legacy call,
>> usb_ether_init(), in a few cases, so that gadget mode ethernet starts.
>> But this leads to the ref counting problems you encountered and
>> re-posted the rejected series for.
> 
> Ok, thanks for the additional details.
> 
> I don't understand why fastboot autoloads the correct gadget driver if
> there is none bound, while all network commands just fail to do that if
> we don't make the usb_ether_init() call manually.

Look into cmd/fastboot.c , it does usb_gadget_initialize(0) , just like 
usb_ether_init() does.

> I also don't understand why I need to unbind the ethernet gadget but I
> cannot bind the fastboot gadget.

Look into cmd/fastboot.c , it does usb_gadget_release() at the end of 
its operation, just like usb_eth_unbind() which is triggered by the 
bind/unbind commands.

> My underlying question is: can we have a single approach for all
> drivers, or is it too complex today? Could it be possible, when we
> perform these autoloads, to look up the registered gadget and
> potentially unbind the one already in place before?

The usb ethernet is special as there is no "ethernet" command like the 
"fastboot" command , which is why it has to be special handled by the 
bind/unbind commands.