On Fri, 2011-05-13 at 14:22 +0200, Stanislaw Gruszka wrote: > On Fri, May 13, 2011 at 01:55:03PM +0200, Johannes Berg wrote: > > > Also in kernel 2.6.39, after driver split into iwlegacy, power save > > > is marked as not supported by driver. I wonder it was deliberate action > > > from Intel developers, or just IEEE80211_HW_SUPPORTS_PS is missed by > > > mistake. I'm going to look at this. > > > > Deliberate. On some platforms/systems, the way the device goes to sleep > > caused DMA trouble or something like that, and the ucode would sysassert > > when it tried to wake itself up. The problem was fairly rare, but of > > course the device wakes up 10 times a second or so ... > > It's interesting if PS on 3945 ever works or was broken from very > beginning. I bet it was, on some old kernel, and this issue is similar > case like most of other bugs we have in iwlwifi - something that worked > well was broken by adding new chipsets/features support, but never fixed > again and just masked/disabled instead. I doubt it, iirc it was just some DMA issue that was discovered at some point and nobody could really pinpoint it. Those old devices stored some internal data into a host memory buffer, and reading them back sometimes corrupted them. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
