[PATCH v2 4/4] drm/verisilicon: check old state CRTC in plane atomic_disable

[Icenowy Zheng]

As atomic_update hooks of both planes would utilize atomic_disable
functions to disable the plane when it's set to invisible (even when
technically enabled), the atomic_disable functions need to check whether
the plane is really enabled before.

Add such a check to prevent NULL dereference.

Fixes: dbf21777caa8 ("drm: verisilicon: add a driver for Verisilicon display controllers")
Fixes: 8c4ae2189125 ("drm: verisilicon: add support for cursor planes")
Signed-off-by: Icenowy Zheng <zhengxingda@xxxxxxxxxxx>
---
 drivers/gpu/drm/verisilicon/vs_cursor_plane.c  | 13 ++++++++++---
 drivers/gpu/drm/verisilicon/vs_primary_plane.c | 13 ++++++++++---
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/verisilicon/vs_cursor_plane.c b/drivers/gpu/drm/verisilicon/vs_cursor_plane.c
index 5295dc2f9ee2e..bee19b65b9a4e 100644
--- a/drivers/gpu/drm/verisilicon/vs_cursor_plane.c
+++ b/drivers/gpu/drm/verisilicon/vs_cursor_plane.c
@@ -104,9 +104,16 @@ static void vs_cursor_plane_atomic_disable(struct drm_plane *plane,
 	struct drm_plane_state *state = drm_atomic_get_old_plane_state(atomic_state,
 								       plane);
 	struct drm_crtc *crtc = state->crtc;
-	struct vs_crtc *vcrtc = drm_crtc_to_vs_crtc(crtc);
-	unsigned int output = vcrtc->id;
-	struct vs_dc *dc = vcrtc->dc;
+	struct vs_crtc *vcrtc;
+	unsigned int output;
+	struct vs_dc *dc;
+
+	if (!crtc)
+		return;
+
+	vcrtc = drm_crtc_to_vs_crtc(crtc);
+	output = vcrtc->id;
+	dc = vcrtc->dc;
 
 	regmap_update_bits(dc->regs, VSDC_CURSOR_CONFIG(output),
 			   VSDC_CURSOR_CONFIG_FMT_MASK,
diff --git a/drivers/gpu/drm/verisilicon/vs_primary_plane.c b/drivers/gpu/drm/verisilicon/vs_primary_plane.c
index e687313d6f057..01725e60e5fbd 100644
--- a/drivers/gpu/drm/verisilicon/vs_primary_plane.c
+++ b/drivers/gpu/drm/verisilicon/vs_primary_plane.c
@@ -65,9 +65,16 @@ static void vs_primary_plane_atomic_disable(struct drm_plane *plane,
 	struct drm_plane_state *state = drm_atomic_get_old_plane_state(atomic_state,
 								       plane);
 	struct drm_crtc *crtc = state->crtc;
-	struct vs_crtc *vcrtc = drm_crtc_to_vs_crtc(crtc);
-	unsigned int output = vcrtc->id;
-	struct vs_dc *dc = vcrtc->dc;
+	struct vs_crtc *vcrtc;
+	unsigned int output;
+	struct vs_dc *dc;
+
+	if (!crtc)
+		return;
+
+	vcrtc = drm_crtc_to_vs_crtc(crtc);
+	output = vcrtc->id;
+	dc = vcrtc->dc;
 
 	regmap_clear_bits(dc->regs, VSDC_FB_CONFIG_EX(output),
 			  VSDC_FB_CONFIG_EX_FB_EN);
-- 
2.56.0