drm/i915: Fix blank panel at reopening lid
When you reopen the lid on a laptop with PCH, the panel suddenly goes
blank sometimes. It seems because BLC_PWM_CPU_CTL register is cleared
to zero when BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1 registers are
enabled.
This patch fixes the problem by moving the call of the function setting
BLC_PWM_CPU_CTL after enabling other two registers.
Reported-and-tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 9474488d..3df4f5f 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -311,9 +311,6 @@
if (dev_priv->backlight_level == 0)
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) {
uint32_t reg, tmp;
@@ -326,7 +323,7 @@
* we don't track the backlight dpms state, hence check whether
* we have to do anything first. */
if (tmp & BLM_PWM_ENABLE)
- return;
+ goto set_level;
if (dev_priv->num_pipe == 3)
tmp &= ~BLM_PIPE_SELECT_IVB;
@@ -347,6 +344,14 @@
I915_WRITE(BLC_PWM_PCH_CTL1, tmp);
}
}
+
+set_level:
+ /* Call below after setting BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1.
+ * BLC_PWM_CPU_CTL may be cleared to zero automatically when these
+ * registers are set.
+ */
+ dev_priv->backlight_enabled = true;
+ intel_panel_actually_set_backlight(dev, dev_priv->backlight_level);
}
static void intel_panel_init_backlight(struct drm_device *dev)