On Tue, Aug 31, 2010 at 07:27:29PM +0200, Martin Fuzzey wrote: > Oliver Neukum wrote: > > You are not handling the case of drivers mapping buffers > > themselves. You need to export this attribute to the drivers. > > > > > This is true. > > Actually I think it is possible for the driver to obtain the value > (albeit in a rather roundabout way): > given a struct usb_device *: > > bus_to_hcd(usb_device->bus)->driver->dma_align_shift > > Granted that is very ugly. I'm also not sure if bus_to_hcd() is intended for > driver use or just the usb core. Just the core. > The last pointer dereference could be avoided by adding the shift to > struct usb_hcd. > However that would mean either making a copy there (which I don't like > much as it violates the Dont Repeat Yourself principle) or using that > instead of struct hc_driver > > I prefer using struct hc_driver since that allows a declarative style > definition in the HCD. > > Or were you thinking of another way entirely of exporting this to the > drivers? How about a simple function that returns the alignment if you need/want it? int usb_device_align_shift(struct usb_device *); It would just do pretty much what you say above, but not force individual drivers to try to figure out the pointer chain themselves. thanks, greg k-h -- 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
