Hi, > > > > On Thu, Dec 19, 2013 at 11:32:08AM +0900, Anton Tikhomirov wrote: > > > > > Hi, > > > > > > > > > > > Hi, > > > > > > > > > > > > On Tue, Dec 17, 2013 at 03:59:31PM +0900, Anton Tikhomirov > wrote: > > > > > > > In accordance with specification, when sent data length is > > > > > > > > > > > > please mention section of specification. > > > > > > > > > > USB2.0 spec., 8.5.3.2 Variable-length Data Stage > > > > > > > > > > > > > > > > > > an exact multiple of wMaxPacketSize for the pipe and less > > > > > > > than requested by host, the function shall return a zero- > length > > > > > > > packet (ZLP) to indicate the end of the Data stage to a USB > host. > > > > > > > > > > > > hmm... so in USB3 mode that would be host requesting 513 > bytes and us > > > > > > sending only 512. > > > > > > > > > > Our customer reported this issue. In their case, Windows USB2.0 > host > > > > > requests Configuration descriptor with wLength = 255. Device > replies > > > > > with two 64 bytes IN transactions, and stalls EP0 on 3rd IN > transaction, > > > > > where it has to reply with ZLP. Unfortunately, we don’t have > full > > > > > picture of what's happening on their side and why host requests > > > > > more bytes than actual length of Configuration descriptor. > > > > > > > > that's a bug on the host side. > > > > > > Certainly not. The host doesn't know how big the Configuration > descriptor > > > is, so it always asks for 255 bytes (on Windows that is, I'm not > sure > > > about Linux). > > > > As far as I know, first time Windows host requests only 9 bytes of > > Configuration descriptor, which include total size of Configuration > > descriptor and its subordinates. Then, second time it requests > > Configuration descriptor again and uses total length obtained in > first > > step. Am I wrong? > > I think it does that for the Device descriptor, but not the > Configuration > descriptor, for some reason. It could depend on which version of > Windows > you have, too. > > My point was that it is not a bug for the host to ask for more bytes > than > the length of the descriptor, just as it is not a bug to ask for fewer > bytes than the length of the descriptor. The device must handle both > cases. Agree. Thanks -- 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
