Re: 2.6.35-rc6 to JuJu firewire issues

From: Stefan Richter
Date: Sat Jul 24 2010 - 08:18:40 EST

Martin Mokrejs wrote:
> I tried in the morning to connect the IcyBox to this laptops internal
> Ricoh Co Ltd R5C552 IEEE 1394 Controller but had issues to power-up the drive
> at all. Not even using USB hub to supply power to it. I connected it to
> the ricoh chip via a 6 to 4 pin cable but also tried the not very good
> Kouwell 7004 PCMCIA card (which does not supply enough power unless I
> buy external, optional power supply of unknown specs and plug it into the
> PCMCIA card).

FireWire CardBus cards do not (or more precisely, must not) provide bus
power at all, unless if they have a power input port and a fitting PSU
is connected to it. If a CardBus card puts power onto the FireWire bus
without any extra PSU connected, then this card is miswired and not spec
compliant. A FireWire bus power provider is required to be able to
deliver 1.5 A current or more, at 8 V or more. That can't be done via

4-pin FireWire ports OTOH do not provide bus power of course; they lack
the respective pins.

Some FireWire disk enclosures can optionally be powered via USB, but we
all know how unreliable USB bus power is. Prefer either a dedicated PSU
or regular FireWire bus power.
Stefan Richter
-=====-==-=- -=== ==---
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at