Commit b1289371 authored by Daniel Vetter's avatar Daniel Vetter

Revert "drm/i915: write backlight harder"

This reverts commit cf0a6584.

Turns out that cargo-culting breaks systems. Note that we can't revert
further, since

commit 770c1231
Author: Takashi Iwai <tiwai@suse.de>
Date:   Sat Aug 11 08:56:42 2012 +0200

    drm/i915: Fix blank panel at reopening lid

fixed a regression in 3.6-rc kernels for which we've never figured out
the exact root cause. But some further inspection of the backlight
code reveals that it's seriously lacking locking. And especially the
asle backlight update is know to get fired (through some smm magic)
when writing specific backlight control registers. So the possibility
of suffering from races is rather real.

Until those races are fixed I don't think it makes sense to try
further hacks. Which sucks a bit, but sometimes that's how it is :(

References: http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg18788.html
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47941Tested-by: default avatarTakashi Iwai <tiwai@suse.de>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: stable@vger.kernel.org (the reverted commit was cc: stable, too)
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 2124b72e
...@@ -321,9 +321,6 @@ void intel_panel_enable_backlight(struct drm_device *dev, ...@@ -321,9 +321,6 @@ void intel_panel_enable_backlight(struct drm_device *dev,
if (dev_priv->backlight_level == 0) if (dev_priv->backlight_level == 0)
dev_priv->backlight_level = intel_panel_get_max_backlight(dev); dev_priv->backlight_level = intel_panel_get_max_backlight(dev);
dev_priv->backlight_enabled = true;
intel_panel_actually_set_backlight(dev, dev_priv->backlight_level);
if (INTEL_INFO(dev)->gen >= 4) { if (INTEL_INFO(dev)->gen >= 4) {
uint32_t reg, tmp; uint32_t reg, tmp;
...@@ -359,12 +356,12 @@ void intel_panel_enable_backlight(struct drm_device *dev, ...@@ -359,12 +356,12 @@ void intel_panel_enable_backlight(struct drm_device *dev,
} }
set_level: set_level:
/* Check the current backlight level and try to set again if it's zero. /* Call below after setting BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1.
* On some machines, BLC_PWM_CPU_CTL is cleared to zero automatically * BLC_PWM_CPU_CTL may be cleared to zero automatically when these
* when BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1 are written. * registers are set.
*/ */
if (!intel_panel_get_backlight(dev)) dev_priv->backlight_enabled = true;
intel_panel_actually_set_backlight(dev, dev_priv->backlight_level); intel_panel_actually_set_backlight(dev, dev_priv->backlight_level);
} }
static void intel_panel_init_backlight(struct drm_device *dev) static void intel_panel_init_backlight(struct drm_device *dev)
......
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