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SubjectRe: [Pcihpd-discuss] Questions about CPCI Hot Swap driver.
On Wed, 29 Jan 2003, Scott Murray wrote:

> > > 2. I wonder why we could not receive the #ENUM interrupt when we unpluged
> > > the board after disabling the corresponding slot("echo 0 > power")? It
> > > seems that the cpci_led_on has some mysterious side effect, but I could
> > > not find any hints in the spec.
> > > Could you help me?
> With most hardware and the current driver, you will still receive an ENUM#
> signal if you flip a card's toggle open after echoing 0 into its power
> file. Since the write to the slot's power file triggers unconfiguration
> of the driver for the attached device and removal of the kernel's PCI
> representation, pulling the card out then triggers the improper removal
> detection logic. I should probably only honor the write of 0 to the
> power file for devices that are in extracting state via a toggle flip,
> I'll experiment a bit to see if that model works.
> However, if the peripheral card in question is a ZT5541, all bets are off,
> since in my experiments here it seems to completely shut down when its
> hotswap LED is toggled. I'm pretty sure this makes it non-compliant with
> PICMG 2.1, but have not decided yet if disabling the attention file is
> worthwhile. We could probably live without the attention file to toggle
> the LED, and theoretically disable_slot should not need to call cpci_led_on
> since clearing EXT is supposed to turn on the LED, but I've not seen
> enough peripheral hardware yet to have a feel for how safe it would be to
> rely on things working correctly on all boards.
The only peripheral board I use is zt5541. And I found the all pci_config_read
return 0xffff after I illuminated the LED.
Thanks for your explanation, it helps me a lot.

Best Regards,
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