Date: Thu, 12 Dec 2013 08:47:02 +0100 From: Hans Petter Selasky <hps@bitfrost.no> To: Kohji Okuno <okuno.kohji@jp.panasonic.com> Cc: freebsd-current@FreeBSD.org, freebsd-usb@freebsd.org Subject: Re: spec violation of xHCI? Message-ID: <52A969F6.3010201@bitfrost.no> In-Reply-To: <52A96276.3060203@bitfrost.no> References: <52A85FAA.8030402@bitfrost.no> <20131211.220615.1986324315440989553.okuno.kohji@jp.panasonic.com> <52A870FA.5080803@bitfrost.no> <20131212.095958.798647707277033359.okuno.kohji@jp.panasonic.com> <52A96276.3060203@bitfrost.no>
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On 12/12/13 08:15, Hans Petter Selasky wrote: > On 12/12/13 01:59, Kohji Okuno wrote: > > Hi Kohji, > > Did you check using a USB analyzer what the difference is when setting > the CHAIN bit and not setting the chain bit? > > I would guess that if you set the CHAIN-bit in this case, no ZLP will be > sent, because the TRB is associated with the previous one. > > What endpoint type is this? BULK/CONTROL/INTR/ISOC > > What direction is this? IN or OUT? > > --HPS Hi Kohji, If there is no CHAIN bit in the IN-direction, my TD chain will receive multiple short packets. This is of course not correct. This only happens if you have very large buffers above 64KByte that don't fit in a single TD. For OUT direction: There are no short packets received, though errors can happen and those will stop the endpoint. Are we sure that by setting the CHAIN bit, that the HC's will transfer ZLP's if the length of the second last "TD" is a multiple of wMaxPacketSize and the last one has a length of zero bytes? I will do some testing to verify the corner cases. Thank you! --HPS
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