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drm/i915: Auto detect DPCD backlight support by default

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Turns out we actually already have some companies, such as Lenovo,
shipping machines with AMOLED screens that don't allow controlling the
backlight through the usual PWM interface and only allow controlling it
through the standard EDP DPCD interface. One example of one of these
laptops is the X1 Extreme 2nd Generation.

Since we've got systems that need this turned on by default now to have
backlight controls working out of the box, let's start auto-detecting it
for systems by default based on what the VBT tells us. We do this by
changing the default value for the enable_dpcd_backlight module param
from 0 to -1.

Tested-by: AceLan Kao <acelan.kao@canonical.com>
Tested-by: Perry Yuan <pyuan@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200116211623.53799-6-lyude@redhat.com
This commit is contained in:
Lyude Paul 2020-01-16 16:16:12 -05:00 committed by Jani Nikula
parent 662884a9ad
commit 9ac7d53d70
2 changed files with 2 additions and 2 deletions
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2
drivers/gpu/drm/i915/i915_params.c
View file

@ -172,7 +172,7 @@ i915_param_named_unsafe(inject_probe_failure, uint, 0400,
i915_param_named(enable_dpcd_backlight, int, 0600,
"Enable support for DPCD backlight control"
"(-1=use per-VBT LFP backlight type setting, 0=disabled [default], 1=enabled)");
"(-1=use per-VBT LFP backlight type setting [default], 0=disabled, 1=enabled)");
#if IS_ENABLED(CONFIG_DRM_I915_GVT)
i915_param_named(enable_gvt, bool, 0400,

2
drivers/gpu/drm/i915/i915_params.h
View file

@ -66,7 +66,7 @@ struct drm_printer;
param(int, reset, 3, 0600) \
param(unsigned int, inject_probe_failure, 0, 0600) \
param(int, fastboot, -1, 0600) \
param(int, enable_dpcd_backlight, 0, 0600) \
param(int, enable_dpcd_backlight, -1, 0600) \
param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE, 0400) \
param(unsigned long, fake_lmem_start, 0, 0400) \
/* leave bools at the end to not create holes */ \