[Intel-gfx] [PATCH] drm/i915: Handle disabled primary plane in debugfs i915_display_info

[Matt Roper]

Now that the primary plane can be disabled independently of the CRTC,
the debugfs code needs to be updated to recognize when the primary plane
is disabled and not try to return information about the primary plane's
framebuffer.

This change prevents a NULL dereference when reading i915_display_info
with a disabled primary plane.

Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index a8b8140..28aa591 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2220,9 +2220,12 @@ static void intel_crtc_info(struct seq_file *m, struct intel_crtc *intel_crtc)
 	struct drm_crtc *crtc = &intel_crtc->base;
 	struct intel_encoder *intel_encoder;
 
-	seq_printf(m, "\tfb: %d, pos: %dx%d, size: %dx%d\n",
-		   crtc->primary->fb->base.id, crtc->x, crtc->y,
-		   crtc->primary->fb->width, crtc->primary->fb->height);
+	if (crtc->primary->fb)
+		seq_printf(m, "\tfb: %d, pos: %dx%d, size: %dx%d\n",
+			   crtc->primary->fb->base.id, crtc->x, crtc->y,
+			   crtc->primary->fb->width, crtc->primary->fb->height);
+	else
+		seq_printf(m, "\tprimary plane disabled\n");
 	for_each_encoder_on_crtc(dev, crtc, intel_encoder)
 		intel_encoder_info(m, intel_crtc, intel_encoder);
 }
-- 
1.8.5.1