On 11/21/2012 05:32 PM, Alan Stern wrote: > 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. > The Ethernet function actually connects over USB within the chip. So managing the power only in the ehci-hcd driver should suffice. cheers, -roger -- 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
