On Tue, 2010-08-03 at 18:11 +0800, Matthias Hopf wrote: > A bit of background about this patch: > > > acpi_video_bus_get_devices() explicitly calls acpi_video_device_enumerate() > before acpi_video_bus_get_one_device(), which does acpi_video_device_bind(). > > In _enumerate(), active_list[] is created, with .bind_info explicitly set to > NULL, while the related .bind_info entry in video_device_list is set to the > acpi_video_device ptr in _bind(). > > The .bind_info is later used in acpi_video_resume() to re-set the backlight > - but it's only evaluated on the active_list[], on which all .bind_info are > NULL by construction. why? .bind_info in active_list is initialized in acpi_video_device_bind. > This results in backlight not being restored, if the > BIOS doesn't do this by itself already. > > > The patch resolves this by replacing the active_list[] traversal by a > video_device_list traversal, > but due to the nature of the issue I'm unsure > whether the original issue isn't of more principal quality. > I don't understand > why the list is (partially) transformed into an array in the first place, > especially as both the array *and* the list are used in the code... > no, the active_list is an array in fact, which equals acpi_video_bus->attached_array. Maybe we need to change it to a more proper name. I'm still wondering why the patch works for you. could you please attach the acpidump output of this laptop? please rebuild your kernel with CONFIG_ACPI_DEBUG=y, and reboot with kernel parameter "acpi.debug_layer=0x10 acpi.debug_level=0x400". and attach the dmesg output after resume, both w/ and w/o the patch you attached. thanks, rui _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
