Should usb_gadget_disconnect() call driver's ->disconnect?
Hi,
Quoted 29 lines · Alan Stern
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The documentation doesn't state whether a gadget driver's ->disconnect() callback will be invoked when
usb_gadget_disconnect()runs. Probably the UDC drivers' behavior has changed over the years.In any case, it's likely that various UDC drivers do behave differently. My current feeling is that ->disconnect() should be invoked only when Vbus turns off, but I can't guarantee that all UDCs will do this.
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my feeling is that ->disconnect() should be called everytime we cause the session to be killed. VBUS Turning off is a guaratee that session is gone, but so is disconnecting data pullup, which is what
usb_gadget_disconnect()does.Okay. I don't mind either way, so long as it is settled.
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How do you feel about documenting this ambiguity as in the patch below? If you think this is okay, I'll submit it formally.
Perhaps a better approach would be to start auditing all UDCs to make sure that ->disconnect() is called when pullup is disconnected. Then we can move ->disconnect() to
usb_gadget_disconnect()itself. No?Rather the other way around: Call ->disconnect() from
usb_gadget_disconnect()itself, then audit all the UDCs to make sure they don't invoke the callbackup. That's better than adding a callback to the UDCs that are missing it, only then to remove it from all of them later on.
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Fair enough. Do you want to handle this or would you prefer that I add to my list?
I'll send in a patch modifying
usb_gadget_disconnect(), and I'll check up on dummy-hcd and net2280. The rest I prefer to leave for you. Okay?
Sure, no issues :)