On Wed, 21 Nov 2012, Roger Quadros wrote: > On 11/21/2012 04:52 PM, Alan Stern wrote: > > On Wed, 21 Nov 2012, Felipe Balbi wrote: > > > >> On Thu, Nov 15, 2012 at 04:34:14PM +0200, Roger Quadros wrote: > >>> From: Andy Green <andy.green@xxxxxxxxxx> > >>> > >>> This patch changes the management of the two GPIO for > >>> "hub reset" (actually controls enable of ULPI PHY and hub reset) and > >>> "hub power" (controls power to hub + eth). > >> > >> looks like this should be done by the hub driver. Alan, what would you > >> say ? Should the hub driver know how to power itself up ? > > > > Not knowing the context, I'm a little confused. What is this hub > > you're talking about? Is it a separate USB hub incorporated into the > > IP (like Intel's "rate-matching" hubs in their later chipsets)? Or is > > it the root hub? > > > > This is actually a USB HUB + Ethernet combo chip (LAN9514) that is hard > wired on the panda board with its Power and Reset pins controlled by 2 > GPIOs from the OMAP SoC. > > When powered, this chip can consume significant power (~0.7 W) because > of the (integrated Ethernet even when suspended. I suppose the ethernet > driver SMSC95XX) doesn't put it into a low enough power state on suspend. > > It doesn't make sense to power the chip when USB is not required on the > whole (e.g. ehci_hcd module is not loaded). This is what this patch is > trying to fix. Ah, okay. Then yes, assuming you want to power this chip only when either ehci-hcd or the ethernet driver is loaded, the right places to manage the power GPIO are in the init and exit routines of the two drivers. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
