[Intel-gfx] [PATCH v2 6/6] drm/i915: Remove most INVALID_PIPE checks from the backlight code

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Now that the backlight device no longer gets registered too early we
should be able to drop most of the INVALID_PIPE checks from the backlight
code.

The only exceptio is the opregion stuff where we may (in theory at
least) get a request from the BIOS already during driver init as soon as
the backlight setup has been done. In which case we can still get the
INVALID_PIPE from intel_get_pipe_from_connector(). So leave that check
in place, and add a comment explaining why.

For the rest, if we still manage to get here with INVALID_PIPE on
VLV/CHV we will now get a WARN from the lower level functions and
can then actually investigate further.

v2: Leave the check in the BIOS related code (Jani)

Cc: Jani Nikula <jani.nikula at intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_panel.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 708642a..c45b127 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -634,10 +634,9 @@ static void intel_panel_set_backlight(struct intel_connector *connector,
 	struct drm_device *dev = connector->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_panel *panel = &connector->panel;
-	enum pipe pipe = intel_get_pipe_from_connector(connector);
 	u32 hw_level;
 
-	if (!panel->backlight.present || pipe == INVALID_PIPE)
+	if (!panel->backlight.present)
 		return;
 
 	mutex_lock(&dev_priv->backlight_lock);
@@ -665,6 +664,12 @@ void intel_panel_set_backlight_acpi(struct intel_connector *connector,
 	enum pipe pipe = intel_get_pipe_from_connector(connector);
 	u32 hw_level;
 
+	/*
+	 * INVALID_PIPE may occur during driver init because
+	 * connection_mutex isn't held across the entire backlight
+	 * setup + modeset readout, and the BIOS can issue the
+	 * requests at any time.
+	 */
 	if (!panel->backlight.present || pipe == INVALID_PIPE)
 		return;
 
@@ -740,9 +745,8 @@ void intel_panel_disable_backlight(struct intel_connector *connector)
 	struct drm_device *dev = connector->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_panel *panel = &connector->panel;
-	enum pipe pipe = intel_get_pipe_from_connector(connector);
 
-	if (!panel->backlight.present || pipe == INVALID_PIPE)
+	if (!panel->backlight.present)
 		return;
 
 	/*
@@ -949,7 +953,7 @@ void intel_panel_enable_backlight(struct intel_connector *connector)
 	struct intel_panel *panel = &connector->panel;
 	enum pipe pipe = intel_get_pipe_from_connector(connector);
 
-	if (!panel->backlight.present || pipe == INVALID_PIPE)
+	if (!panel->backlight.present)
 		return;
 
 	DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));
-- 
2.0.4