[PATCH] drm/i915: do not disable backlight on vgaswitcheroo switch off

[PATCH] drm/i915: do not disable backlight on vgaswitcheroo switch off

[Jani Nikula]

On muxed systems, the other vgaswitcheroo client may depend on i915 to
handle the backlight. We began switching off the backlight since

commit a261b246ebd552fd5d5a8ed84cc931bb821c427f
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Jul 26 19:21:47 2012 +0200

    drm/i915: disable all crtcs at suspend time

breaking backlight on discreet graphics in (some) muxed systems.

Keep the backlight on when the state is changed through vgaswitcheroo.

Note: The alternative would be to add a quirk table to achieve the same
based on system identifiers, but AFAICS it would asymptotically approach
effectively the same as this patch as more IDs are added, but with the
maintenance burden of the quirk table.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=55311
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59785
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/intel_panel.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 67e2c1f..1062154 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -515,6 +515,17 @@ void intel_panel_disable_backlight(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	unsigned long flags;
 
+	/*
+	 * Do not disable backlight on the vgaswitcheroo path. When switching
+	 * away from i915, the other client may depend on i915 to handle the
+	 * backlight. This will leave the backlight on unnecessarily when
+	 * another client is not activated.
+	 */
+	if (dev->switch_power_state == DRM_SWITCH_POWER_CHANGING) {
+		DRM_DEBUG_DRIVER("Skipping backlight disable on vga switch\n");
+		return;
+	}
+
 	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
 
 	dev_priv->backlight.enabled = false;
-- 
1.7.9.5

Re: [PATCH] drm/i915: do not disable backlight on vgaswitcheroo switch off

[Jani Nikula]

On Thu, 25 Jul 2013, Jani Nikula <jani.nikula@intel.com> wrote:
> On muxed systems, the other vgaswitcheroo client may depend on i915 to
> handle the backlight. We began switching off the backlight since
>
> commit a261b246ebd552fd5d5a8ed84cc931bb821c427f
> Author: Daniel Vetter <daniel.vetter@ffwll.ch>
> Date:   Thu Jul 26 19:21:47 2012 +0200
>
>     drm/i915: disable all crtcs at suspend time
>
> breaking backlight on discreet graphics in (some) muxed systems.
>
> Keep the backlight on when the state is changed through vgaswitcheroo.
>
> Note: The alternative would be to add a quirk table to achieve the same
> based on system identifiers, but AFAICS it would asymptotically approach
> effectively the same as this patch as more IDs are added, but with the
> maintenance burden of the quirk table.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=55311

Tested-by: Fede <fedevx@yahoo.com>
Tested-by: Aximab <laurent.debian@gmail.com>

> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59785

Tested-by: sfievet <sebastien.fievet@free.fr>

> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_panel.c |   11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 67e2c1f..1062154 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -515,6 +515,17 @@ void intel_panel_disable_backlight(struct drm_device *dev)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	unsigned long flags;
>  
> +	/*
> +	 * Do not disable backlight on the vgaswitcheroo path. When switching
> +	 * away from i915, the other client may depend on i915 to handle the
> +	 * backlight. This will leave the backlight on unnecessarily when
> +	 * another client is not activated.
> +	 */
> +	if (dev->switch_power_state == DRM_SWITCH_POWER_CHANGING) {
> +		DRM_DEBUG_DRIVER("Skipping backlight disable on vga switch\n");
> +		return;
> +	}
> +
>  	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
>  
>  	dev_priv->backlight.enabled = false;
> -- 
> 1.7.9.5
>

-- 
Jani Nikula, Intel Open Source Technology Center

Re: [PATCH] drm/i915: do not disable backlight on vgaswitcheroo switch off

[Daniel Vetter]

On Wed, Aug 07, 2013 at 09:26:34AM +0300, Jani Nikula wrote:
> On Thu, 25 Jul 2013, Jani Nikula <jani.nikula@intel.com> wrote:
> > On muxed systems, the other vgaswitcheroo client may depend on i915 to
> > handle the backlight. We began switching off the backlight since
> >
> > commit a261b246ebd552fd5d5a8ed84cc931bb821c427f
> > Author: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Date:   Thu Jul 26 19:21:47 2012 +0200
> >
> >     drm/i915: disable all crtcs at suspend time
> >
> > breaking backlight on discreet graphics in (some) muxed systems.
> >
> > Keep the backlight on when the state is changed through vgaswitcheroo.
> >
> > Note: The alternative would be to add a quirk table to achieve the same
> > based on system identifiers, but AFAICS it would asymptotically approach
> > effectively the same as this patch as more IDs are added, but with the
> > maintenance burden of the quirk table.
> >
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=55311
> 
> Tested-by: Fede <fedevx@yahoo.com>
> Tested-by: Aximab <laurent.debian@gmail.com>
> 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59785
> 
> Tested-by: sfievet <sebastien.fievet@free.fr>

Picked up for -fixes (with a cc: stable), thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch