On 05/02/2014 07:56 PM, Rafael J. Wysocki wrote: > On Friday, May 02, 2014 11:32:15 AM Hans de Goede wrote: >> Hi All, >> >> I was already considering asking for $subject for a while, but I did not see >> any bug reports caused by it so I didn't ask. Until today I discovered that >> I'm not seeing any bugs because Fedora is carrying a kernel patch >> changing the default. >> >> A quick google search for brightness_switch_enabled OTOH reveals that for >> other distros it is a serious problem, see ie: >> https://bugs.launchpad.net/gnome-settings-daemon/+bug/527157 >> http://askubuntu.com/questions/173921/why-does-my-thinkpad-brightness-control-skip-steps >> >> The problem is that acpi-video is unique in that it not only generates >> brightness up/down keypresses, but also (sometimes) actively changes the >> brightness itself. >> >> This presents an inconsistent kernel interface to userspace, basically there >> are 2 different scenarios, depending on the laptop model: >> >> 1) On some laptops a brightness up/down keypress means: show a brightness osd >> with the current brightness, iow it is a brightness has changed notification. >> >> 2) Where as on (a lot of) other laptops it means a brightness up/down key was >> pressed, deal with it. >> >> Most of the desktop environments interpret any press as in scenario 2, and >> change the brightness up / down as a response to the key events, causing it >> to be changed twice, once by acpi-video and once by the DE. >> >> With the new default for video.use_native_backlight we will be moving even >> more laptops over to behaving as in scenario 2. Making the remaining laptops >> even more of a weird exception. Also note that it is hard to detect scenario >> 1 properly in userspace, and AFAIK none of the DE-s deasls with it. >> >> Therefor I would like to propose to change the brightness_switch_enabled >> default to 0. > > Aaron, what do you think about that? Personally, I like this. Last time I remembered, people who do not use GUI or use a simple GUI which does not provide handling of backlight events prefer to having this param default to 1(and they have a working acpi_video interface of course). But I suppose most people are using a GUI that handles such events and the in kernel handling of backlight events is indeed unique for acpi_video and cause in consistence with other backlight control interfaces, I think it is a good thing to set brightness_switch_enabled to 0 by default. Thanks, Aaron -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
