[Intel-gfx] [PATCH 6/5] drm/i915: Make sure the primary plane is enabled before reading out the fb state

[Damien Lespiau]

We don't want to end up in a state where we track that the pipe has its
primary plane enabled when primary plane registers are programmed with
values that look possible but the plane actually disabled.

Refuse to read out the fb state when the primary plane isn't enabled.

Suggested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Suggested-by: Matt Roper <matthew.d.roper at intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 074f204..3fe9598 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6613,6 +6613,10 @@ i9xx_get_initial_plane_config(struct intel_crtc *crtc,
 	struct drm_framebuffer *fb;
 	struct intel_framebuffer *intel_fb;
 
+	val = I915_READ(DSPCNTR(plane));
+	if (!(val & DISPLAY_PLANE_ENABLE))
+		return;
+
 	intel_fb = kzalloc(sizeof(*intel_fb), GFP_KERNEL);
 	if (!intel_fb) {
 		DRM_DEBUG_KMS("failed to alloc fb\n");
@@ -6621,8 +6625,6 @@ i9xx_get_initial_plane_config(struct intel_crtc *crtc,
 
 	fb = &intel_fb->base;
 
-	val = I915_READ(DSPCNTR(plane));
-
 	if (INTEL_INFO(dev)->gen >= 4)
 		if (val & DISPPLANE_TILED)
 			plane_config->tiling = I915_TILING_X;
@@ -7654,6 +7656,9 @@ skylake_get_initial_plane_config(struct intel_crtc *crtc,
 	fb = &intel_fb->base;
 
 	val = I915_READ(PLANE_CTL(pipe, 0));
+	if (!(val & PLANE_CTL_ENABLE))
+		goto error;
+
 	if (val & PLANE_CTL_TILED_MASK)
 		plane_config->tiling = I915_TILING_X;
 
@@ -7741,6 +7746,10 @@ ironlake_get_initial_plane_config(struct intel_crtc *crtc,
 	struct drm_framebuffer *fb;
 	struct intel_framebuffer *intel_fb;
 
+	val = I915_READ(DSPCNTR(pipe));
+	if (!(val & DISPLAY_PLANE_ENABLE))
+		return;
+
 	intel_fb = kzalloc(sizeof(*intel_fb), GFP_KERNEL);
 	if (!intel_fb) {
 		DRM_DEBUG_KMS("failed to alloc fb\n");
@@ -7749,8 +7758,6 @@ ironlake_get_initial_plane_config(struct intel_crtc *crtc,
 
 	fb = &intel_fb->base;
 
-	val = I915_READ(DSPCNTR(pipe));
-
 	if (INTEL_INFO(dev)->gen >= 4)
 		if (val & DISPPLANE_TILED)
 			plane_config->tiling = I915_TILING_X;
-- 
1.8.3.1