Hi, On Fri, Aug 19, 2011 at 10:34:29PM -0400, Alan Stern wrote: > On Sat, 20 Aug 2011, Felipe Balbi wrote: > > > On Sat, Aug 20, 2011 at 12:33:01AM +0200, Michal Nazarewicz wrote: > > > From: Michal Nazarewicz <mina86@xxxxxxxxxx> > > > > > > This commit renames the “speed” field of the usb_gadget_driver > > > structure to “max_speed”. This is so that to make it more > > > apparent that the field represents the maximum speed gadget > > > driver can support. > > > > > > This also make the field look more like fields with the same > > > name in usb_gadget and usb_composite_driver structures. All > > > of those represent the *maximal* speed given entity supports. > > > > > > After this commit, there are the following fields in various > > > structures: > > > * usb_gadget::speed - the current connection speed, > > > * usb_gadget::max_speed - maximal speed UDC supports, > > > > this will be handled inside the UDC itself, so why do you need to expose > > it ? > > I wondered about this too. It turns out that sometimes the gadget > driver really does need to know about the maximum speed supported by > the UDC hardware and driver. > > For example, suppose the gadget driver and the UDC both support high > speed, but the gadget is currently plugged into a USB-1.1 controller > and therefore running only at full speed. Then the gadget driver has > to respond to the Get-Device-Qualifier and Get-Other-Speed-Config > requests by sending the appropriate descriptors. But if the UDC > doesn't support high speed operation then the gadget driver has to > respond to those requests with a STALL. aa, good point :-) -- balbi
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