diff options
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index 96fe3eaba44a..8b9c925c4c16 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -456,11 +456,17 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector) } /* - * A lot of eDP panels in the wild will report supporting both the - * Intel proprietary backlight control interface, and the VESA - * backlight control interface. Many of these panels are liars though, - * and will only work with the Intel interface. So, always probe for - * that first. + * Since Intel has their own backlight control interface, the majority of machines out there + * using DPCD backlight controls with Intel GPUs will be using this interface as opposed to + * the VESA interface. However, other GPUs (such as Nvidia's) will always use the VESA + * interface. This means that there's quite a number of panels out there that will advertise + * support for both interfaces, primarily systems with Intel/Nvidia hybrid GPU setups. + * + * There's a catch to this though: on many panels that advertise support for both + * interfaces, the VESA backlight interface will stop working once we've programmed the + * panel with Intel's OUI - which is also required for us to be able to detect Intel's + * backlight interface at all. This means that the only sensible way for us to detect both + * interfaces is to probe for Intel's first, and VESA's second. */ if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector)) { drm_dbg_kms(dev, "Using Intel proprietary eDP backlight controls\n"); |