[Intel-gfx] [PATCH] drm/i915: Add breadcrumbs for why the backlight is being set

[Chris Wilson]

At the moment we have 3 paths that lead to actually_set_backlight(),
from modesetting, ACPI/OpRegion requests and our very own
intel_backlight interface, and we have no way of distinguishing them in
the debug log. So add a debug breadcrumb to explain the source of the
backlight changes.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_opregion.c | 1 +
 drivers/gpu/drm/i915/intel_panel.c    | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
index 2acf5cae20e4..564da613b278 100644
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -405,6 +405,7 @@ static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
 	if (bclp > 255)
 		return ASLC_BACKLIGHT_FAILED;
 
+	DRM_DEBUG_KMS("updating opregion backlight %d/255\n", bclp);
 	intel_panel_set_backlight(dev, bclp, 255);
 	iowrite32(DIV_ROUND_UP(bclp * 100, 255) | ASLE_CBLV_VALID, &asle->cblv);
 
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 54684168de1e..1f2996031ad9 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -574,6 +574,8 @@ void intel_panel_enable_backlight(struct drm_device *dev,
 		intel_pipe_to_cpu_transcoder(dev_priv, pipe);
 	unsigned long flags;
 
+	DRM_DEBUG_KMS("pipe=%d\n", pipe);
+
 	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
 
 	if (dev_priv->backlight.level == 0) {
@@ -680,6 +682,8 @@ intel_panel_detect(struct drm_device *dev)
 static int intel_panel_update_status(struct backlight_device *bd)
 {
 	struct drm_device *dev = bl_get_data(bd);
+	DRM_DEBUG_KMS("updating intel_backlight, brightness=%d/%d\n",
+		      bd->props.brightness, bd->props.max_brightness);
 	intel_panel_set_backlight(dev, bd->props.brightness,
 				  bd->props.max_brightness);
 	return 0;
-- 
1.8.4.rc3