[Intel-gfx] [PATCH 1/2] i915/debug: Expose crtc dither state via debugfs

[Bhanuprakash Modem]

[Why]
It's useful to know the dithering state for IGT testing.

[How]
Expose the dithering state for the crtc via a debugfs file "dither".

Example usage: cat /sys/kernel/debug/dri/0/crtc-0/dither

Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 94ed442910d6..18646566f2ea 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1902,13 +1902,30 @@ static const struct i915_debugfs_files {
 #endif
 };
 
+static int dither_state_show(struct seq_file *m, void *data)
+{
+	struct intel_crtc *crtc = to_intel_crtc(m->private);
+	struct intel_crtc_state *crtc_state = to_intel_crtc_state(crtc->base.state);
+
+	seq_printf(m, "Dither: %u\n", crtc_state->dither);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(dither_state);
+
 void i915_debugfs_register(struct drm_i915_private *dev_priv)
 {
 	struct drm_minor *minor = dev_priv->drm.primary;
+	struct drm_device *dev = &dev_priv->drm;
+	struct drm_crtc *crtc;
 	int i;
 
 	i915_debugfs_params(dev_priv);
 
+	drm_for_each_crtc(crtc, dev)
+		debugfs_create_file("dither", S_IRUGO, crtc->debugfs_entry, crtc,
+				&dither_state_fops);
+
 	debugfs_create_file("i915_forcewake_user", S_IRUSR, minor->debugfs_root,
 			    to_i915(minor->dev), &i915_forcewake_fops);
 	for (i = 0; i < ARRAY_SIZE(i915_debugfs_files); i++) {
-- 
2.20.1