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authorLyude Paul <lyude@redhat.com>2021-03-18 20:02:02 +0300
committerRodrigo Vivi <rodrigo.vivi@intel.com>2021-04-12 15:00:24 +0300
commit11664169981a025b7f6072d136ac724294b7b65c (patch)
tree3d83837b5123bdb770b60bbe62852399d26adc94 /drivers/gpu
parentd434405aaab7d0ebc516b68a8fc4100922d7f5ef (diff)
downloadlinux-11664169981a025b7f6072d136ac724294b7b65c.tar.xz
drm/i915/dpcd_bl: Don't try vesa interface unless specified by VBT
Looks like that there actually are another subset of laptops on the market that don't support the Intel HDR backlight interface, but do advertise support for the VESA DPCD backlight interface despite the fact it doesn't seem to work. Note though I'm not entirely clear on this - on one of the machines where this issue was observed, I also noticed that we appeared to be rejecting the VBT defined backlight frequency in intel_dp_aux_vesa_calc_max_backlight(). It's noted in this function that: /* Use highest possible value of Pn for more granularity of brightness * adjustment while satifying the conditions below. * ... * - FxP is within 25% of desired value. * Note: 25% is arbitrary value and may need some tweak. */ So it's possible that this value might just need to be tweaked, but for now let's just disable the VESA backlight interface unless it's specified in the VBT just to be safe. We might be able to try enabling this again by default in the future. Fixes: 2227816e647a ("drm/i915/dp: Allow forcing specific interfaces through enable_dpcd_backlight") Cc: Jani Nikula <jani.nikula@intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Bugzilla: https://gitlab.freedesktop.org/drm/intel/-/issues/3169 Signed-off-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210318170204.513000-1-lyude@redhat.com (cherry picked from commit 9e2eb6d5380e9dadcd2baecb51f238e5eba94bee) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c1
1 files changed, 0 insertions, 1 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 651884390137..4f8337c7fd2e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -646,7 +646,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
break;
case INTEL_BACKLIGHT_DISPLAY_DDI:
try_intel_interface = true;
- try_vesa_interface = true;
break;
default:
return -ENODEV;