Re: [RFC/PATCH] usb: misc: Add a driver for TC7USB40MU

Quoting Peter Chen (2016-09-13 20:32:00)

On Tue, Sep 13, 2016 at 06:42:46PM -0700, Stephen Boyd wrote:

quoted

On the db410c 96boards platform we have a TC7USB40MU[1] on the
board to mux the D+/D- lines from the SoC between a micro usb
"device" port and a USB hub for "host" roles. Upon a role switch,
we need to change this mux to forward the D+/D- lines to either
the port or the hub. Therefore, introduce a driver for this
device that intercepts extcon USB_HOST events and logically
asserts a gpio to mux the "host" D+/D- lines when a host cable is
attached. When the cable goes away, it will logically deassert
the gpio and mux the "device" lines.

Would you please draw the design? It can also help me review your
chipidea patch well.

1. How many ports on the board?
2. How the lines are connected on the board?

The schematic for the db410c is publically available here[2][3].

There's also the 96boards spec[4] which talks about this switch based
design a little bit. See the section titled "Single USB port Example".

[2] https://github.com/96boards/documentation/blob/master/ConsumerEdition/DragonBoard-410c/HardwareDocs/Schematics_DragonBoard.pdf
[3] https://github.com/96boards/documentation/raw/master/ConsumerEdition/DragonBoard-410c/HardwareDocs/Schematics_DragonBoard.pdf
[4] https://www.96boards.org/wp-content/uploads/2015/02/96BoardsCESpecificationv1.0-EA1.pdf