On Friday, October 11, 2013 06:01:43 PM Josh Boyer wrote: > On Fri, Oct 11, 2013 at 6:10 PM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > On Friday, October 11, 2013 12:42:43 PM Josh Boyer wrote: > >> On Fri, Oct 11, 2013 at 9:27 AM, Aaron Lu <aaron.lu@xxxxxxxxx> wrote: > >> > v5: > >> > 1 Introduce video.use_native_backlight module parameter and set its > >> > value to false by default as suggested by Rafael. For Win8 systems > >> > which have broken ACPI video backlight control, the parameter can be > >> > set to 1 in kernel cmdline to skip registering ACPI video's backlight > >> > interface. Due to this change, the acpi_video_verify_backlight_support > >> > is moved from video_detect.c to video.c - patch 3/4; > >> > >> That's a fairly untenable position for distro kernels to be in. They > >> now have to ask every user that reports an issue with the backlight to > >> try setting that option on the command line. While I appreciate the > >> setting breaks things for some people, doesn't the Win8 issue impact > >> far more people? Shouldn't it be defaulted to true? > > > > Well, we have a rule in the kernel not to introduce regressions for users even > > if they are minority. > > > >> If nothing else, can you add a config option for the default so > >> distros can use that to decide which way to default it and then work > >> on fixing the remaining users that have troubles? > > > > The current plan is to create a blacklist of systems where that option should > > be set. We actually already have one, but it is at the _OSI() level, which > > is overkill in my view and may affect things beyond backlight. Along with that > > we will debug systems where setting that option (to true) causes problems to > > happen, so that we'll be able to drop it going forward (hopefully). > > > > Of course, distro kernels may always change the default to true if they want. > > They can, but they'd need to either patch the kernel to do so, or code > it in userspace bootloader configs. Having a config option they can > set to change the default makes it reasonable and contained within the > kernel. If we are to use a Kconfig option, why don't we use one instead of rather than in addition to a command line option? Say, we have CONFIG_ACPI_VIDEO_WIN8_WORKAROUND and if that is set, the code will work like the previous version of the Aaron's patchset (the one without video.use_native_backlight)? Opinions? -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
