On Mon, 29 Jul 2019, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: > at 16:26, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote: > >> On Tue, 23 Jul 2019, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: >>> Hi, >>> >>> Currently, OLED panel brightness [1] is not supported. >> >> As a general statement this is not true, and not backed up by the >> referenced bug. We just don't know how brightness is controlled on that >> particular laptop, because it apparently uses a properietary mechanism. >> >> If it used the brightness control mechamism specified in the VESA eDP >> spec, it should work just fine with the i915 aux backlight support, and >> we should also export the regular backlight sysfs for this. > > I am told that Windows introduced “NitsBrightness” [1] to support OLED panel. > I don’t know how it’s plumbed to the aux interface though. That would be about what the numbers we expose to userspace mean. That's a completely different problem from the kernel not being able to adjust the brightness of a panel, OLED or not, via the DPCD because of the non-standard interface being used. BR, Jani. > > Is it possible to ask Windows graphics team how Windows handle OLED panel? > > [1] > https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/content/d3dkmdt/ns-d3dkmdt-_dxgk_brightness_caps > > Kai-Heng > >> >> BR, >> Jani. >> >> >>> We have a similar Dell system that also affect by lack of OLED brightness >>> support. >>> >>> I’ve investigated both kernel and user space but I haven’t found a good >>> general solution yet. >>> Dell systems use EDID descriptor 4 as Dell specific descriptor, which >>> reports its panel type and we can know it’s an OLED panel or not. >>> >>> My initial thought is to add a new attribute “oled" in drm_sysfs.c [2] to >>> let userspace like clutter [3] to control the brightness. >>> However other DEs may need to implement their own OLED brightness support >>> which isn’t ideal. >>> >>> So I’d like to know if there’s any good way to support OLED brightness in >>> good old backlight sysfs, to let userspace keep to the current interface. >>> >>> [1] https://bugs.freedesktop.org/show_bug.cgi?id=97883 >>> [2] https://pastebin.ubuntu.com/p/QYrRBppVT9/ >>> [3] >>> https://gitlab.gnome.org/GNOME/clutter/blob/master/clutter/clutter-brightness-contrast-effect.c#L559 >>> >>> Kai-Heng >> >> -- >> Jani Nikula, Intel Open Source Graphics Center > > -- Jani Nikula, Intel Open Source Graphics Center _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
