On Mon, Aug 24, 2015 at 02:17:08PM -0400, Alan Stern wrote: > On Mon, 24 Aug 2015, Felipe Balbi wrote: > > > > Maybe we should add a vendor-specific control request to gadget Zero so > > > that the host can tell the gadget what the transfer size will be. > > > > I proposed that many months ago and you were against it, remember ? > > I believe you -- it sounds like the sort of thing I might say -- but I > don't remember it. :-) > > > You claimed that there should be no issues with gadget and host not > > agreeing on transfer size, which actually makes sense, considering we > > have no idea what the host will send us until it does (except for things > > like BOT). > > > > If we add this vendor control request, we are likely to leave some > > issues in UDCs making assumptions as to what they should receive next. > > These are good arguments. The only place an issue arises, as far as I > can see, is in the pattern=2 data. Where should the pattern reset back > to the start? At the beginning of each packet? At the beginning of > each transfer? At the beginning of each test? > > The difficulty is that the host and gadget don't have any common > notions about transfers or tests. That leaves only packets (or maybe > bursts/multiplets for isochronous). Before each test, there is a set_alt, we can have a vendor request before that, the content of this request can be transfer length, pattern , and so on which the host and device needs to be aligned during the test. I send this email is just want to see if usbtest/g_zero can be easier to use, and test more things without user interfere. -- Best Regards, Peter Chen -- 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
