From: Felipe Balbi <felipe.balbi@linux.intel.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: USB list <linux-usb@vger.kernel.org>
Subject: Should usb_gadget_disconnect() call driver's ->disconnect?
Date: Wed, 08 Aug 2018 10:24:07 +0300 [thread overview]
Message-ID: <874lg5ianc.fsf@linux.intel.com> (raw)
Hi,
Alan Stern <stern@rowland.harvard.edu> writes:
> Felipe:
>
> 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.
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.
> 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?
next reply other threads:[~2018-08-08 7:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-08 7:24 Felipe Balbi [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-08-10 6:59 Should usb_gadget_disconnect() call driver's ->disconnect? Felipe Balbi
2018-08-09 14:04 Alan Stern
2018-08-09 12:10 Felipe Balbi
2018-08-08 14:14 Alan Stern
2018-08-07 19:24 Alan Stern
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