Re: [RFC][PATCH 2/3] usb: roles: Add usb role switch notifier.

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Hi,

On 18-10-2019 21:53, John Stultz wrote:
On Fri, Oct 18, 2019 at 12:30 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Looking at drivers/usb/typec/tcpm/tcpci.c: tcpci_set_vconn I see that
there is a data struct with vendor specific callbacks and that the
drivers/usb/typec/tcpm/tcpci_rt1711h.c implements that.

So you may want something similar here. But things are tricky here,
because when nothing is connected you want to provide Vbus for
the USB-A ports, which means that if someone then connects a
USB-A to C cable to connect the board to a PC (switching the port
to device mode) there will be a time when both sides are supplying
5V if I remember the schedule correctly.

Ok. Thanks for the pointer, I'll take a look at that to see if I can
get it to work.

I think that the original hack might not be that bad, the whole hw
design seems so, erm, broken, that you probably cannot do proper
roleswapping anyways.  So just tying Vbus to host mode might be
fine, the question then becomes again how can some other piece
of code listen to the role-switch events...

So, at least in the current approach (see the v3 series), I've
basically set the hub driver as an role-switch intermediary, sitting
between the calls from the tcpm to the dwc3 driver. It actually works
better then the earlier notifier method (which had some issues with
reliably establishing the initial state on boot).  Does that approach
work for you?

That sounds like it might be a nice solution. But I have not seen the
code, I think I was not Cc-ed on v3. Do you have a patchwork or
lore.kernel.org link for me?

Regards,

Hans





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