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drm/i915/backlight: Remove try_vesa_interface

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Some panels need VESA DPCD AUX backlight but VBT says otherwise.
This is why we try with Intel backlight interface over VESA backlight
interface. This causes a blankout on such panels without any fallback
mechanism.
Remove try_vesa_interface and use VESA AUX backlight interface as a
fallback mechanism.
While at in sneak in a small comment cleanup too.

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15679
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20260224031322.2568874-1-suraj.kandpal@intel.com
This commit is contained in:
Suraj Kandpal
2026-02-24 08:43:22 +05:30
parent 4226479f91
commit 40d2f58209
1 changed files with 7 additions and 12 deletions
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19
drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
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@@ -644,9 +644,10 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
struct intel_dp *intel_dp = intel_attached_dp(connector);
struct drm_device *dev = connector->base.dev;
struct intel_panel *panel = &connector->panel;
bool try_intel_interface = false, try_vesa_interface = false;
bool try_intel_interface = false;
/* Check the VBT and user's module parameters to figure out which
/*
* Check the VBT and user's module parameters to figure out which
* interfaces to probe
*/
switch (display->params.enable_dpcd_backlight) {
@@ -655,7 +656,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
case INTEL_DP_AUX_BACKLIGHT_AUTO:
switch (panel->vbt.backlight.type) {
case INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE:
try_vesa_interface = true;
break;
case INTEL_BACKLIGHT_DISPLAY_DDI:
try_intel_interface = true;
@@ -668,20 +668,12 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
if (panel->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)
try_intel_interface = true;
try_vesa_interface = true;
break;
case INTEL_DP_AUX_BACKLIGHT_FORCE_VESA:
try_vesa_interface = true;
break;
case INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL:
try_intel_interface = true;
break;
}
/* For eDP 1.5 and above we are supposed to use VESA interface for brightness control */
if (intel_dp->edp_dpcd[0] >= DP_EDP_15)
try_vesa_interface = true;
/*
* 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
@@ -694,6 +686,9 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
* 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.
*
* Also there is a chance some VBTs may advertise false Intel backlight support even if the
* TCON DPCD says otherwise. This means we keep VESA interface as fallback in that case.
*/
if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector) &&
intel_dp->edp_dpcd[0] <= DP_EDP_14b) {
@@ -703,7 +698,7 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
return 0;
}
if (try_vesa_interface && intel_dp_aux_supports_vesa_backlight(connector)) {
if (intel_dp_aux_supports_vesa_backlight(connector)) {
drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using VESA eDP backlight controls\n",
connector->base.base.id, connector->base.name);
panel->backlight.funcs = &intel_dp_vesa_bl_funcs;