Hi, On 10/24/22 15:32, Dmitry Osipenko wrote: > Chromebooks don't have backlight in ACPI table, they suppose to use > native backlight in this case. Check presence of the CrOS embedded > controller ACPI device and prefer the native backlight if EC found.
Thank you for this patch! > Suggested-by: Hans de Goede <[email protected]> > Fixes: b1d36e73cc1c ("drm/i915: Don't register backlight when another > backlight should be used (v2)") > Signed-off-by: Dmitry Osipenko <[email protected]> > --- > drivers/acpi/video_detect.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c > index 0d9064a9804c..8ed5021de6fb 100644 > --- a/drivers/acpi/video_detect.c > +++ b/drivers/acpi/video_detect.c > @@ -668,6 +668,11 @@ static const struct dmi_system_id > video_detect_dmi_table[] = { > { }, > }; > > +static bool google_cros_ec_present(void) > +{ > + return acpi_dev_found("GOOG0004"); > +} > + > /* > * Determine which type of backlight interface to use on this system, > * First check cmdline, then dmi quirks, then do autodetect. > @@ -730,6 +735,9 @@ static enum acpi_backlight_type > __acpi_video_get_backlight_type(bool native) > return acpi_backlight_video; > } > > + if (google_cros_ec_present()) > + return acpi_backlight_native; > + Nice, a couple of remarks: 1. Maybe add a small comment explaining why, like all the other tests in the function have a small comment ? 2. I think it would be better to do: if (google_cros_ec_present() && native_available) return acpi_backlight_native; I can e.g. imagine in the future some chromebooks where for some reason native GPU backlight control is not available using the EC for backlight control and then having the chrome-ec code register a backlight with "vendor" type ? 3. This will also trigger on the Framework laptops and possible other new non Chromebook designs which choose to use the Chrome EC code for their EC, I don't expect these devices to get to this point of __acpi_video_get_backlight_type() (they will hit the earlier acpi_video / native paths) but still I want to at least point this out in case someone sees a potential issue with this? If you can address 1. and 2. from above (or explain why 2. is a bad idea) then I believe that the next version of this can get merged to resolve the chromebook backlight issues introduced in 6.1-rc1, thank you! > /* No ACPI video (old hw), use vendor specific fw methods. */ > return acpi_backlight_vendor; > } Regards, Hans
