AW: [U-Boot-Users] LITE5200 board: Bus Fault with 2 network cards
mark.jonas at freescale.com
Tue Jul 13 09:47:40 CEST 2004
Martin Krause wrote:
>>Is there a known issue with the PCI on the MPC5200, and more specifically
>>with PCI network cards ?
>I also have problems with some PCI cards. Some are recognized, some not. I haven't found an explanation, yet. I guess it has something to do with some "3.3 V compatible" cards are not really compatible with 3.3 V only systems. It could as well be an errata in the MPC5200 described in the MPC5200 Errata Listing:
>ID 322: Violation of PCI Tval min time
>The PCI Timing Speci?cation de?nes the timing parameter Tval (CLK to Signal Valid Delay):
> Tval min 2 ns, max 11 ns (33MHz)
> Tval min 2 ns, max 6 ns (66MHz)
> When M66EN is asserted, the minimum speci?cation for Tval(min) may be reduced to 1 ns if a mechanism is provided to guarantee a minimum value of 2 ns when M66EN is deasserted.
>MPC5200 provides Tval min of 1 ns (instead of 2 ns), which is a violation of the
>Timing Speci?cation for 33MHz.
Yes, some cards are not detected because of this errata. Please note
that this only happens if the card / chipset used is also not PCI timing
spec compliant. A compliant card / chipset needs to be able to handle 0
ns Tval(min). And some cards say "3.3 V compatible" but they aren't
because either 3.3 V is simply not enough or they do nasty things like
shortening the 5 V and 3.3 V power supply. That's always worth a check
before inserting the card in a 3.3 V / 5 V system.
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