Re: [PATCH 3/3] i915: Don't provide ACPI backlight interface iffirmware expects Windows 8

[Alex Deucher]

Radeon probably needs something similar.  See attached untested patch.

Alex

On Sun, Jun 9, 2013 at 7:01 PM, Matthew Garrett
<matthew.garrett@xxxxxxxxxx> wrote:
> Windows 8 leaves backlight control up to individual graphics drivers rather
> than making ACPI calls itself. There's plenty of evidence to suggest that
> the Intel driver for Windows doesn't use the ACPI interface, including the
> fact that it's broken on a bunch of machines when the OS claims to support
> Windows 8. The simplest thing to do appears to be to disable the ACPI
> backlight interface on these systems.
>
> Signed-off-by: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 3b315ba..23b6292 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>                 /* Must be done after probing outputs */
>                 intel_opregion_init(dev);
>                 acpi_video_register();
> +               /* Don't use ACPI backlight functions on Windows 8 platforms */
> +               if (acpi_osi_version() >= ACPI_OSI_WIN_8)
> +                       acpi_video_backlight_unregister();
>         }
>
>         if (IS_GEN5(dev))
> --
> 1.8.2.1
>
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From c6ead3429fd3977b4b2ee5748d83c72272592b29 Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher@xxxxxxx>
Date: Mon, 10 Jun 2013 10:05:43 -0400
Subject: [PATCH] drm/radeon: don't provide ACPI backlight if firmware expects
 Windows 8

Windows 8 leaves backlight control up to individual graphics drivers rather
than making ACPI calls itself.

Untested.

Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
---
 drivers/gpu/drm/radeon/atombios_encoders.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
index 4120d35..bc9e007 100644
--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -233,6 +233,10 @@ void radeon_atom_backlight_init(struct radeon_encoder *radeon_encoder,
 
 	DRM_INFO("radeon atom DIG backlight initialized\n");
 
+	/* Don't use ACPI backlight functions on Windows 8 platforms */
+	if (acpi_osi_version() >= ACPI_OSI_WIN_8)
+		acpi_video_backlight_unregister();
+
 	return;
 
 error:
-- 
1.7.7.5