On Wed, 12 Nov 2014, Sean O. Stalley wrote: > On Tue, Nov 11, 2014 at 10:54:30AM -0500, Alan Stern wrote: > > On Mon, 10 Nov 2014, Stephanie Wallick wrote: > > > > > +static struct mausb_hcd mhcd; > > > > Only one statically-allocated structure? What if somebody wants to > > have more than one of these things in their system? > > > > Our plan to support multiple MA devices is to have them all connected > to the same virtual host controller, so only 1 would be needed. > > Would you prefer we have 1 host controller instance per MA device? > We are definitely open to suggestions on how this should be architected.
I haven't read the MA USB spec, so I don't know how it's intended to work. Still, what happens if you create a virtual host controller with, say, 16 ports, and then someone wants to connect a 17th MA device? Also, I noticed that your patch adds a new bus type for these MA host controllers. It really seems like overkill to have a whole new bus type if there's only going to be one device on it. > If we get rid of these locks, endpoints can't run simultaneously. > MA USB IN endpoints have to copy data, which could take a while. I don't know what you mean by "run simultaneously". Certainly multiple network packets can be transmitted and received concurrently even if you use a single spinlock, since your locking won't affect the networking subsystem. > Couldn't this cause a bottleneck? Probably not enough to matter. After all, the other host controller drivers rely on a single spinlock. And if it did matter, you could drop the spinlock while copying the data. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
