From 22505b82a2800bddb67908522833bef96dd15845 Mon Sep 17 00:00:00 2001 From: Aaron Lu Date: Fri, 2 Aug 2013 09:16:03 +0800 Subject: drm/i915: avoid brightness overflow when doing scale Some card's max brightness level is pretty large, e.g. on Acer Aspire 4732Z, the max level is 989910. If user space set a large enough level then the current scale done in intel_panel_set_backlight will cause an integer overflow and the scaled level will be mistakenly small, leaving user with an almost black screen. This patch fixes this problem. Signed-off-by: Aaron Lu [danvet: Add a comment to explain what's going on.] Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_panel.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/i915/intel_panel.c') diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 67e2c1f1c9a..5063eadac3e 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -497,8 +497,11 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level, u32 max) goto out; } - /* scale to hardware */ - level = level * freq / max; + /* scale to hardware, but be careful to not overflow */ + if (freq < max) + level = level * freq / max; + else + level = freq / max * level; dev_priv->backlight.level = level; if (dev_priv->backlight.device) -- cgit v1.2.3-70-g09d2 From 3f577573cd5482a32f85bd131e52f7cb4b9ac518 Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Thu, 25 Jul 2013 14:31:30 +0300 Subject: drm/i915: do not disable backlight on vgaswitcheroo switch off 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 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 Tested-by: Aximab Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59785 Tested-by: sfievet Signed-off-by: Jani Nikula Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_panel.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/gpu/drm/i915/intel_panel.c') diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 5063eadac3e..5950888ae1d 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -518,6 +518,17 @@ 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; -- cgit v1.2.3-70-g09d2