[v2,4/5] drm/i915: Auto detect DPCD backlight support by default
diff mbox series

Message ID 1effc5c8688803cae96d6c3dbbc447998cab8f56.1579010266.git.jani.nikula@intel.com
State New
Headers show
Series
  • drm/i915: eDP DPCD aux backlight fixes
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Commit Message

Jani Nikula Jan. 14, 2020, 2:01 p.m. UTC
From: Lyude Paul <lyude@redhat.com>

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>
---
 drivers/gpu/drm/i915/i915_params.c | 2 +-
 drivers/gpu/drm/i915/i915_params.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Patch
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diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 1dd1f3652795..31eed60c167e 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -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,
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 31b88f297fbc..a79d0867f77a 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -64,7 +64,7 @@  struct drm_printer;
 	param(int, reset, 3) \
 	param(unsigned int, inject_probe_failure, 0) \
 	param(int, fastboot, -1) \
-	param(int, enable_dpcd_backlight, 0) \
+	param(int, enable_dpcd_backlight, -1) \
 	param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE) \
 	param(unsigned long, fake_lmem_start, 0) \
 	/* leave bools at the end to not create holes */ \