On Wed, May 23, 2018 at 10:03:55AM -0400, Alan Stern wrote: > On Wed, 23 May 2018, Nicolas Boichat wrote: > > > The "old" enumeration scheme is considerably faster (it takes > > ~294ms instead of ~439ms to get the descriptor). > > > > It is currently only possible to use the old scheme globally > > (/sys/module/usbcore/parameters/old_scheme_first), which is not > > desirable as the new scheme was introduced to increase compatibility > > with more devices. > > > > However, in our case, we care about time-to-active for a specific > > USB device (which we make the firmware for), on a specific port > > (that is pogo-pin based: not a standard USB port). This new > > sysfs option makes it possible to use the old scheme on a single > > port only. > > > > Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx> > > --- > > > > There are other "quirks" that we could add to reduce further > > enumeration time (e.g. reduce USB debounce time, reduce TRSTRCY > > to 10ms instead of 50ms as used currently), but the logic is quite > > similar, so it'd be good to have this reviewed first. > > I'm not opposed to the idea in principle, although I don't like your > implementation because it breaks the original old_scheme_first > parameter. > > Let's see what some other people think. > > Yours is a rather special case, because you know exactly what device > will be attached to a specific port. Still, I can see that sort of > thing happening in constrained and special-purpose settings. > > How do you arrange to set the new quirk before the device is > discovered? Yeah, this last question is what I had when looking at this. Or does it not matter at first boot and only matters for wake-up? 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
