On 08/12/2013 05:07 AM, Mark Rutland wrote: > [Adding Olof] > > On Mon, Aug 12, 2013 at 10:51:36AM +0100, Mark Brown wrote: >> On Sun, Aug 11, 2013 at 09:53:01PM -0400, Alan Stern wrote: >>> On Sun, 11 Aug 2013, Mark Brown wrote: >> >>>> One example that's bugging me right now is that on the Insignal Arndale >>>> platform there's a USB hub connected to one of the USB ports on the SoC >>>> (not as a PHY, it seems we also need the internal PHY running to talk to >>>> the device). The hub needs to be "plugged" into the SoC after the SoC >>>> USB controller has started with some GPIOs so we need to tell the system >>>> that the hub exists and needs to be synchronised with the USB controller. ... > As I understand it, the wifi chip on the Snow Chromebook has a similar > issue -- it hangs off of a probeable SDIO bus, but needs a regulator > poked for it to turn on and become probeable (see > exynos_wifi_bt_set_power in [1]). In this case, I wonder if it makes sense to model the extra requirements as part of the bus/socket/... itself rather than as part of the device that's attached to the bus. It seems quite common for SDIO-based WiFi devices to need a few things: * Regulator * 32KHz clock * Enable GPIO (-> rfkill?) * Perhaps a reset GPIO Physically, these are provided to the socket into which the WiFi device plugs in. Perhaps we should try to explicitly model the socket (which I guess is really the SDIO bus in a way) rather than attaching these new resources to the controller or the device itself. In a similar way, I wonder if the USB case can be considered the same way? This seems less like a good fit since I don't expect the resources are always so similar there, and also there's the case of the bus being potentially behind a few levels of USB hub. And of course it all gets a little more messy when you get board-specific logic that needs setup, rather than something more common across multiple devices. -- 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
