On Mon, 14 Apr 2014, Laurent Pinchart wrote: > Hello, > > The PXA27x OHCI implementation doesn't perform automatic control of port power > supplies for all ports. While the PPS and LSDA bits of the HcRhPortStatus > register are implemented, only a subset of ports have an external power enable > pin controlled by the port status register. Other ports need their power supply > to be controlled manually. > > In order to do so I've implemented manual regulator control in the ohci-pxa27x > driver. This requires overriding the default behaviour of the CLEAR_FEATURE > and SET_FEATURE requests for USB_PORT_FEAT_POWER with a custom hub control > operation. In turn this requires calling the currently static ohci_hub_control > function from the ohci-pxa27x driver. > > The ohci-s3c2410 driver already implements a similar feature, and accesses the > ohci_hub_control function by saving the struct hc_driver hub_control value to > a global variable right after calling ohci_init_driver. This is a bit of a > hack, and as I need to call that function as well I've decided to export it > instead. It only seems like a hack if you don't think about it the right way. :-) The intention was to imitate an object-oriented style, by allowing a child class to override member functions in the parent class. The vtable mechanism in C++, for example, does essentially the same thing as ohci-s3c2410 (except that C++ doesn't save the original function pointer in a global variable; instead it reads the function pointer from the parent's vtable as needed -- ohci-s3c2410 can't do that because ohci_hc_driver isn't exported). I'm open to the idea of exporting the hub functions. In the end, it doesn't make all that much difference (it would save a little object code). > Another option would have been to handle the regulators directly inside the > ohci-hub implementation, but I'm not sure whether it's worth it yet. Comments > (or acks :-)) will be appreciated. > > Please not that I haven't been able to test the third patch due to lack of > hardware. I've however tested a similar implementation on an out of tree > PXA270 board. > > Laurent Pinchart (3): > USB: OHCI: Export the ohci_hub_control function > USB: ohci-pxa27x: Add support for external vbus regulators > ARM: pxa: zeus: Replace OHCI init/exit functions with a regulator > > arch/arm/mach-pxa/zeus.c | 89 ++++++++++++++++++++++------------------- > drivers/usb/host/ohci-hub.c | 4 +- > drivers/usb/host/ohci-pxa27x.c | 67 +++++++++++++++++++++++++++++++ > drivers/usb/host/ohci-s3c2410.c | 7 +--- > drivers/usb/host/ohci.h | 2 + > 5 files changed, 121 insertions(+), 48 deletions(-) You missed ohci-at91.c. And ehci-tegra.c plays similar games. I'd prefer to do the same thing for both ehci-hcd and ohci-hcd. 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
