On Sun, Jul 20, 2008 at 10:27 PM, Andrew Daviel <advax@xxxxxxxxx> wrote: > > On Mon, Apr 21, 2008 at 4:58 PM, Eero Tamminen <eero.tamminen@xxxxxxxxx> > wrote: >> One possibility is a WLAN AP with broken power management > > I recently noticed that my tablet battery runs down faster at work than > at home, with the WiFi enabled but otherwise sitting idle (12%/hour vs > 1%/hour). > > I thought the issue might be that there's more broadcast/multicast > traffic at work, which would get through the filters in the ethernet chip > and into the kernel, but then I found a reference to your post on the > list. > > At home I have a Linksys WRT54; at work I think Orinoco-AP2000 where I > may be able to change some settings (writing this at home I can't login > to check). > > What power-management issues have you seen affecting battery life ? I think it is usually caused by interoperability deficiency between 770/n8x0 and some routers wifi chipset regarding PSM (Power Saving Management) part of wifi specification. I'm seeing this kind of issue between my work AP (Linksys) which have working PSM and my home AP (Freebox, a set-top-box provided by my ISP), where PSM is not working properly with a maximum uptime of 8h when wifi is on. I've been in contact with one of my ISP engineers who is taking care of writing wifi driver in their set-top-box. From the first investigation, it seems Conexant chip (used on Nokia tablets) was known to be problematic (Freebox is using Ralink chipset). A first bug was found in ralink proprietary driver which was losing AP association after some time in PSM mode, which was fixed by Ralink. Unfortunately, this fix was not sufficient to fix the power consumption issue and we are kind of stuck now :( If Eero or another Nokia hackers have some information which might help Freebox engineers to track the issue, I'll be happy to serve as a proxy. > Would it affect other laptops as well or just the tablets ? I guess it will depend on laptop wifi chipset. And compared to Nokia tablets, entire laptop power consumption is way more important than a tablet, so if wifi is too important, it is probably hidden by other component consumption. -- Frederic Crozat _______________________________________________ maemo-users mailing list maemo-users@xxxxxxxxx https://lists.maemo.org/mailman/listinfo/maemo-users
