http://bugzilla.kernel.org/show_bug.cgi?id=12748
--- Comment #17 from Henrique de Moraes Holschuh <h...@hmh.eng.br> 2009-05-05 02:20:38 --- We shouldn't go turning ACPI power states to OFF if the BIOS handled the device already turned ON (with the power source enabled as well). Turning resources off when we are not sure they're unused is bound to cause problems, it will disturb devices like boot-media on USB, etc. It is a _VERY_ Bad Idea. Instead, we should go over the entire list, attach all power resources according to the *current* state of the device. Lots of devices will _already_ be at D0 state, and we must attach the power resources to them before we start turning them off. We must not turn a power resource off until we can be sure that there are NO devices using it. So, we'd need something like my patch (but covering pnp as well), to attach the resources to devices already in D0. Then, we must find opportune times to do a scan and turn off any unattached resources. These are: when we disable any device, during suspend and resume, and after we are sure we attached resources to every device already enabled (even to those without drivers, as modules might be loaded later). The above is not very difficult, but it is just half the job. What is troublesome is the fact that we will never disable *all* devices we enable (because there are buggy PCI crap that we cannot resurrect back to D0 when we place it in D3, etc). And the current power resource code takes pointers (in the linked lists) back to the devices. We must change this, because the modules must still be allowed to unload, and in that case, the power resource must not still hold a reference to an area of memory that is now invalid. We will have to change the power resources to use reference counting or something else. Drivers that do not disable devices on unload will cause the power resource to never turn off, but that's alright - the device is still on, anyway. -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ------------------------------------------------------------------------------ The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com _______________________________________________ acpi-bugzilla mailing list acpi-bugzilla@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/acpi-bugzilla
