Hi Peter,
Thanks for your patch. If an OTG capable port doesn't have a way to detect its
initial role based on cable detection, I think it's somehow dangerous to give
the port to host controller. When the port is enabled for host role, platform
starts supplying VBUS to the connector. If the connector happens to be connected
to a host role port which is supplying VBUS as well, there could be some damage
to the board which doesn't have proper protection.
Thanks,
JC
On 9/8/20 11:01 PM, Peter Geis wrote:
> Prior to implementing role switch support, all enabled ports enumerated
> as host devices.
> With role switch support enabled, device trees with otg ports which have
> not been updated with usb-role-switch support now bail out during
> enumeration.
> This disables all xhci ports tied to the affected phy.
>
> Retain backwards compatibility by forcing host mode on otg ports which
> are missing the usb-role-switch flag.
> Disable ports explicitly defined as peripheral mode that are missing the
> usb-role-switch flag.
>
> Signed-off-by: Peter Geis <pgwipeout@xxxxxxxxx>
> Reported-by: Matias Zuniga <matias.nicolas.zc@xxxxxxxxx>
>
> Fixes: e8f7d2f409a1 ("phy: tegra: xusb: Add usb-phy support")
> ---
> drivers/phy/tegra/xusb.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c
> index de4a46fe1763..c36dce13e0c6 100644
> --- a/drivers/phy/tegra/xusb.c
> +++ b/drivers/phy/tegra/xusb.c
> @@ -734,10 +734,12 @@ static int tegra_xusb_usb2_port_parse_dt(struct tegra_xusb_usb2_port *usb2)
> err = tegra_xusb_setup_usb_role_switch(port);
> if (err < 0)
> return err;
> + } else if (usb2->mode == USB_DR_MODE_PERIPHERAL) {
> + dev_err(&port->dev, "mandatory usb-role-switch not found for %s mode, disabling port\n", modes[usb2->mode]);
> + usb2->mode = USB_DR_MODE_UNKNOWN;
> } else {
> - dev_err(&port->dev, "usb-role-switch not found for %s mode",
> - modes[usb2->mode]);
> - return -EINVAL;
> + dev_warn(&port->dev, "usb-role-switch not found for %s mode, forcing host\n", modes[usb2->mode]);
> + usb2->mode = USB_DR_MODE_HOST;
> }
> }
>
>
