[PATCH] USB: initialize or shutdown PHY when add or remove host controller

Felipe Balbi balbi at ti.com
Tue Jun 18 11:00:50 EDT 2013


On Tue, Jun 18, 2013 at 10:53:26AM -0400, Alan Stern wrote:
> > > If the controllers don't want HCD core to manage the PHY they can just set it
> > > to some error code.
> > 
> > they shouldn't have the choice, otherwise it'll be a bit of a PITA to
> > maintain the code. ehci core tries to grab the PHY, if it's not there,
> > try to continue anyway. Assume it's not needed.
> Felipe, are all these issues straightened out to your satisfaction?  I
> can't tell from the email thread.
> Looking through the EHCI glue source files, there appears to be a 
> variety of different ways of getting the PHY.  It's not at all clear 
> that they can be moved into the ehci-hcd core (or even better, the USB 
> core -- which is what Chao is trying to do).

yeah, Roger brought up a big problem with OMAP's EHCI depending on the
mode so, at least for now, we should keep phy_get and, in case of EHCI
OMAP, phy_init in the glue :-(

Roger has all the details, and they're also in the list archives, but
basically, depending on the mode, PHY *must* be initialized at a
particular point.

> Given that the glue module has to be responsible for getting the PHY,
> it should also be responsible for error checking.  So the code added to
> hcd.c doesn't need to apply an IS_ERR check; it can simply assume that
> if hcd->phy is NULL then either there is no software-controllable PHY
> or else the HCD doesn't want the core to manage it.

makes sense to me, add the requirement to:

if (IS_ERR(hcd->phy))
	hcd->phy = NULL;

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