PCMCIA issue

Sebastian M=?ISO-8859-1?B?/A==?=sch sebastian at sebastian-muesch.de
Tue Aug 30 23:52:23 UTC 2005


Hi,

Once upon a time Ian K wrote:
> I am still getting no product info available. The interuppts line
> from /proc/interrupts is still there.

And it should indeed ... Every autonomous component (your
pcmcia-network-adapter too) within you pc needs an "interrupt-channel" (so
called IRQ) ... On this "channel" the device can interrupt the normal
cpu-processing, and forcing the cpu to do some io-work with the device. The
problem is if more than one device is using the same channel, like humans
not all devices are able to share something and it seems like your
pcmcia-controller or your pcmcia-network adapter is one of these devices ;-)

> Can you kind of explain this a little further, Im not very
> familiar with IRQs.

These days there are two automatic ways on a pc available, how a device
get's it's interrupt:

1. The old way: BIOS
The Bios does a almost random mapping for the interrupts (random in the
sense, that it is not device specific) ... This method is not used while
hotplugging a device. If only this way of automatic mapping is available,
the pcmcia-controller will try manual mapping.
2. The new way: ACPI
The ACPI-interface ask the devices, what they are capable of, and then does
the mapping. If this festure is available the pcmcia-controller will first
ask the device, what it's capable of. As not all devices support this
"feature" there can be a problem too. That's why you should disable acpi
with the kernel-params.

If you insert a pcmcia-card, the pcmcia-controller throws an interrupt,
telling the cpu "There's a new device on the bus man!". Then the
yanta-driver would select an interrupt for the new device, loads the driver
and after this the device should be functional

Your problem is (maybe). The pcmcia-controller cannot tell the kernel
"There's a new device!" OR the device itself doesn't work on a specific
interrupt, is not capable of sharing an interrupt with another device, ...
For the second problem you can try to force the controller not to map the
"new device" to a specific (already used) irq, by adding a exlude-line to
the pcmcia-config, that's it.

Cu
Sebastian

-- 
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     _ :'_
   .`_`-'_`.     Sebastian Müsch
  :__|\ /|__:      sebastian at sebastian-muesch.de
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