drm/vc4: crtc: Add some logging

The encoder retrieval code has been a source of bugs and glitches in the
past and the crtc <-> encoder association been wrong in a number of
different ways.

Add some logging to quickly spot issues if they occur.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20211025152903.1088803-7-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_crtc.c

@@ -541,6 +541,9 @@ static void vc4_crtc_atomic_disable(struct drm_crtc *crtc,
 	struct drm_encoder *encoder = vc4_get_crtc_encoder(crtc, old_state);
 	struct drm_device *dev = crtc->dev;
 
+	drm_dbg(dev, "Disabling CRTC %s (%u) connected to Encoder %s (%u)",
+		crtc->name, crtc->base.id, encoder->name, encoder->base.id);
+
 	require_hvs_enabled(dev);
 
 	/* Disable vblank irq handling before crtc is disabled. */
@@ -572,6 +575,9 @@ static void vc4_crtc_atomic_enable(struct drm_crtc *crtc,
 	struct drm_encoder *encoder = vc4_get_crtc_encoder(crtc, new_state);
 	struct vc4_encoder *vc4_encoder = to_vc4_encoder(encoder);
 
+	drm_dbg(dev, "Enabling CRTC %s (%u) connected to Encoder %s (%u)",
+		crtc->name, crtc->base.id, encoder->name, encoder->base.id);
+
 	require_hvs_enabled(dev);
 
 	/* Enable vblank irq handling before crtc is started otherwise