Date: Tue, 4 May 2004 09:18:29 +0200 From: "Daan Vreeken [PA4DAN]" <Danovitsch@Vitsch.net> To: Julian Elischer <julian@elischer.org> Cc: FreeBSD-current@FreeBSD.org Subject: Re: USB isochronous transfers Message-ID: <200405040918.29117.Danovitsch@Vitsch.net> In-Reply-To: <Pine.BSF.4.21.0405031729390.40085-100000@InterJet.elischer.org> References: <Pine.BSF.4.21.0405031729390.40085-100000@InterJet.elischer.org>
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On Tuesday 04 May 2004 02:32, Julian Elischer wrote: > On Tue, 4 May 2004, John Birrell wrote: > > Are there any USB experts here? > > > > The ugen driver in current has code that treats an isochronous endpoint > > which has a wMaxPacketSize of zero as invalid and won't open it. > > > > I have a board here that reports it's isochronous endpoint like that. > > > > On page 47 of the USB Specification 2.0, I see this: > > > > "All device default interface settings must not include any isochronous > > endpoints with non-zero data payload sizes (specified via wMaxPacketSize > > in the endpoint descriptor). Alternate interface settings may specify > > non-zero data payload sizes for isochronous operation." > > > > My board is supposed to be a reference implementation from Philips > > for their 1581 USB chip and their MPEG2 chips. It only has the default > > interface. > > I had a look in my USB book (The mindshare USB2 book) but it didn't > illuminate the subject any more than what you have already found.. > The whole concept of all those descriptors and how they all fit together > is confusing at the best of times. Maybe a bit off-topic, but even if ugen would accept it, you would probably crash your system using it ;-) The ugen driver has a pointer error in the isochronous transfer code. I have filed a PR about it with a patch more than a year ago, but it's still in the code today... Could someone please apply the fix in : kern/51074: pointer arithmatic error in ugen.c And when you're at it have a look at another PR (with patch) I have sent in that prevents all USB if_* drivers from crashing with more than one device plugged in : kern/59290: [PATCH] attaching more than one of the same usb if_* adapters crashes system Thanks, Daan
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