weird SDIO interrupt and SDIO mechanism

[Holger Schurig]

> Do the USB and CF interface have the same phenomena ?

Not for CF. I only get interrupts for:

* TX packet sent
* RX packet received
* CMD upload done
* CMD response ready
* events, e.g link lost

For example, I have a VNC server on my device now running for 19 
minutes (and regularly updating parts of the screen) and so far 
I have only about 13500 interrupts:

cat /proc/interrupts
           CPU0
 86:      13532        GPIO  libertas_cs

Even then i2c controller generates more interrupts here, despite 
it being used only to ask for the battery level ...


For USB, this depends on your USB controller. Some USB 
controllers (eg. the crappy Cypress SL811HS) generate interrupts 
at a rate of 1000 Hz (or was it 100 Hz, not sure) because of the 
constant polling needed for the USB protocol.