Re: Problems getting the 1394 ROM configuration info

From: Jeff Henkels (jeff_at_mapson.privatemail.com)
Date: 08/14/04 

Date: Sat, 14 Aug 2004 11:58:25 -0700

"BJ Johns" <hjohns1@ix.netcom.com> wrote in message
news:OJ8bYg6fEHA.1656@TK2MSFTNGP10.phx.gbl...
> I am new to device drivers and am working on a driver for a 1394 firewire
> video device. I am having some problems in getting the ROM configuration
> info.
>
> I am able to perform multiple async reads of 4 bytes at a time to read the
> ROM data starting at 0xFFFFFF0000400 and continuing until I have read the
> entire contents of the config info. And I have verified that all of the
> retrieved data is correct.

So, how do you figure out how many quadlets you have to read to get the
entire config ROM? I'd like to try this method next.

> But if I try to read anything more than 4 bytes at a time, I just get all
> zero's back. First question....Is there a limit to the number of bytes
that
> can be retrieved at a time when reading the ROM config info?
>
> Next, I tried calling REQUEST_GET_CONFIGURATION_INFO in the
IOCTL_1394_CLASS
> to get the buffer sizes of the Unit Directory, Unit Dependent Directory,
> Vendor Leaf and Model Leaf by first setting each of these values to zero
> before making the call. After returning success, the call only seems to
set
> the u.GetConfigurationInformation.UnitDirectoryBufferSize value to 12
(which
> is incorrect) and leaves all others at zero.

I've noticed this too; I've been working with the 1394DCAM DDK sample, which
uses REQUEST_GET_CONFIGURATION_INFO. My guess, based on one or two things
I've read here in this group, is that the 1394 class driver assumes a
specific format for the config ROM and gets confused if the format isn't
what it expects.

> Why does it not return the correct values?
>
> At worst case I can just take the retrieved data from my first technique
and
> extract the same information as the call
> to REQUEST_GET_CONFIGURATION_INFO should have done but I want to find out
> why this call doesn't seem to work for me.
>
> Thanks
> -BJ
>
>

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