Quoting Peter Chen (2017-01-02 22:53:19)

On Wed, Dec 28, 2016 at 02:57:09PM -0800, Stephen Boyd wrote:

quoted

If the phy supports it, call phy_set_mode() to pull up D+ when
required by setting the mode to PHY_MODE_USB_DEVICE. If we want
to remove the pullup, set the mode to PHY_MODE_USB_HOST.

[..]

quoted

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 0d532a724d48..6d61fa0689b0 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c

@@ -1609,10 +1610,15 @@ static int ci_udc_pullup(struct usb_gadget *_gadget, int is_on)
              return 0;
 
      pm_runtime_get_sync(&ci->gadget.dev);
-     if (is_on)
+     if (is_on) {
+             if (ci->phy)
+                     phy_set_mode(ci->phy, PHY_MODE_USB_DEVICE);
              hw_write(ci, OP_USBCMD, USBCMD_RS, USBCMD_RS);
-     else
+     } else {
              hw_write(ci, OP_USBCMD, USBCMD_RS, 0);
+             if (ci->phy)
+                     phy_set_mode(ci->phy, PHY_MODE_USB_HOST);
+     }
      pm_runtime_put_sync(&ci->gadget.dev);
 
      return 0;

Would you describe the use case for it? Why not adding it at
role switch routine?

This is about pulling up D+. The phy I have requires that we manually
pull up D+ by writing a ULPI register before we set the run/stop bit. I
thought it would be appropriate to do so in ci_udc_pullup(), where we're
supposed to put that pullup code, unless I'm mistaken?

It's not exactly about putting the phy into device or host mode, so
phy_set_mode() may not actually be the best API to use. Perhaps we need
some sort of phy_pullup_usb() API here?