Date: Sun, 26 Jul 1998 16:02:35 -0400 From: Brad Karp <karp@eecs.harvard.edu> To: freebsd-mobile@FreeBSD.ORG Subject: 12V power for PC-Cards? Message-ID: <199807262002.QAA29797@dominator.eecs.harvard.edu>
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My Motorola PM100C CDPD modem/radio is a type II PC-Card. It works reasonably well (i.e., as well as one can expect from CDPD) for wireless IP, with the exception that its 9V alkaline internal battery runs out far too quickly. Motorola supports "partial host power," which it is claimed will allow the radio to work for a much longer period on a single battery. In this mode, the PC-Card draws 12V from the laptop. Of course this will run down the laptop battery much more rapidly, but for applications where the laptop has an AC source, but no network connection, this power mode is a vast improvement. (Note that Motorola bizarrely neglects to offer a direct external AC power supply option for the card while it runs; they only offer an external charger and NiCad battery for the card, which requires the battery be removed from the card during charging. And of course, the NiCad battery has an even lesser capacity than a standard alkaline 9V cell.) I have learned the undocumented AT commands to make the Motorola card take 12V from the laptop to use this partial host power mode. Using (also undocumented) status AT commands, I learned that my laptop, an IBM 380D with a Cirrus PD672X PCIC, will not supply the Motorola with 12V when it is inserted. I have verified with pccardc dumpcis that the card's CIS tuples include a request for 12V, and with pccardc rdreg that the behavior of 2.2.6 leaves the power register for the slot in question with the 12V bit cleared. For the moment, I work around the problem by manually using pccardc to change the power register for the slot with the Motorola card to a value with the 12V bit turned on. This works just fine; when I query the card after hand- tweaking this register, it reports that it is receiving 12V from the laptop. My rather cursory reading of the pccardd and sys/pccard code gives me the impression that apart from an unused ioctl for setting the power values for a slot, there is no support in either 2.2-stable or 3.0-current for giving cards 12V when they ask for it. My question is, am I right? Has there been little demand for 12V, so that the pccard code doesn't check for the request from the card and configure the slot accordingly? Or am I missing the place that is meant to take care of this in the code, and the code is simply not working on my hardware? I would be happy to contribute code to handle 12V requests, if there is interest. Comments? -Brad, karp@eecs.harvard.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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