On Fri, Oct 11, 2013 at 4:27 PM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > 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? If you only have a config option, users can't override the distro settings. If you simply have a config option for the default value, the distros can set it without having to carry a patch (the primary benefit), but users can still override that without having to rebuild a kernel. josh _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
