Bug#644174: Probable cause of freeze of Dell Vostro 3750, when booting with device connected to USB 3.0 jack

[wzab <wzab@ise.pw.edu.pl>]

I have found some facts which hopefully may explain the problems with 
booting of Dell Vostro 3750.

1. The system hangs, when it attempts to service cooling devices 
controlled via SMBus
2. The SMBus controller and the USB 3.0 controller share the same IRQ 18 
line (is it a standard solution or design flaw?)
3. The interrupt service routine in the i2c-smbus.c driver seems not to
support shared interrupts.

All above findings are described in more detailed way in the bug report:
https://bugzilla.kernel.org/show_bug.cgi?id=42844

particularly:
https://bugzilla.kernel.org/show_bug.cgi?id=42844#c11
https://bugzilla.kernel.org/show_bug.cgi?id=42844#c13
https://bugzilla.kernel.org/show_bug.cgi?id=42844#c15
https://bugzilla.kernel.org/show_bug.cgi?id=42844#c16

HTH & Regards,
Wojtek Zabolotny