Date: Mon, 15 Apr 2002 10:47:25 -0700 From: Peter Haight <peterh@sapros.com> To: Nick Hibma <n_hibma@van-laarhoven.org> Cc: hardware@freebsd.org Subject: Re: Reading from the USB ugen device. Message-ID: <200204151747.g3FHlPRg037046@wartch.sapros.com>
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>> From what you told me and a brief look at the USB spec, I'm guessing it >> isn't a coincidence that it is failing on that read where I'm expecting 64 >> bytes (the max size of a USB packet payload). I'm guessing that in short >> read mode, the driver gets a full length packet and is expecting another >> data packet but it never comes because that's the end of the data, so it >> doesn't return from the read until it gets a timeout. > >No. If you read 64 byes in 64 bytes with short_XFER switched on you will >be reading 64 bytes and then 0 bytes. Ok. But why does this happen: read(3, 0x8091800, 1024) read -1 bytes At that same point in the protocol if I do: read(3, 0x8091800, 64) read 64 bytes I would expect: read(3, 0x8091800, 1024) read 64 bytes To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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