Re: [pci] BUS Mastering & TRDY generation ?

[cfk <cfk@pacbell.net>]

Dear Gustaw:
    Well, for the first time ever, I now can say that the PCI Wishbone
bridge will generate TRDY when reading vendor/deviceID. I can now admire
that fact that a transaction completes sufficient to see on my logic
analyzer both a TRDY assertion by the bridge and the default vendor/deviceID
at dword zero of "00012321". It is loaded into a Xilinx VirtexE 2000 chip. I
can tell you that I had some trouble with the fact that the IDSEL needed to
be set correctly. I did not get TRDY until the IDSEL was set to an address
bit that my host was asserting. In my particular case, I am not using a PC,
I have a vxWorks host connected directly to the bridge and I can see with
the logic analyzer that it scans from AD[18]..AD[31]. I suspect that most
motherboards do not scan AD[11]..AD[15] as I received an e-mail from a
friend that told me the default setting of AD[11] in the testbench (which I
used for my hardware) was wrong and the PCI spec indicates that PCI bridges
talking to the PCI-Wishbone bridge will not scan AD[11]. So, all I can tell
you is that it works, it reads configurations space back (at least dword
zero), I'm tired and tomorrow is another day.

Charles

----- Original Message -----
From: <Gustaw47@poczta.onet.pl>
To: <pci@opencores.org>
Sent: Monday, June 17, 2002 8:17 AM
Subject: [pci] BUS Mastering & TRDY generation ?


> Hi all,
>
> I try to implement BUS Mastering on my PCI Card.
> The card asserts REQ , Mainboard asserts GNT. Then I invoke addres
> phase : Memory Read + some addres (tried different adresses), IRDY.
> Mainboard still holds GNT (bus is mine) but never asserts TRDY so no
> data can be transferred.
> Finally I must deassert REQ and transaction fails to complete.
>
> What could be a reason that Mainboard doesn't assert TRDY ? I work in
> the simplest enviroment : DOS, Real mode, software in ASM.
>
> The second question is:
> If I use BAR Registers and reserve some MEMORY space for my card,
> where phisically will it be located ? On mainboard's SD-RAM or in my
> card's S-RAM ?
>
> Maybe I post trivial questions, but I didn't find any information about it
> anywhere, even in PCI SIG Specifications ...
>
> Thanks in advance,
> Gustaw Mazurek, Warsaw.
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