[Intel-gfx] [PATCH 1/4] drm/i915/gen9: Avoid using negative array index in skl_update_plane()

[Imre Deak]

scaler_id may be negative as shown by conditions later in the function,
so don't use it as an array index in that case.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/intel_sprite.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 0f3e230..286bcc6 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -203,8 +203,6 @@ skl_update_plane(struct drm_plane *drm_plane,
 	uint32_t y = plane_state->src.y1 >> 16;
 	uint32_t src_w = drm_rect_width(&plane_state->src) >> 16;
 	uint32_t src_h = drm_rect_height(&plane_state->src) >> 16;
-	const struct intel_scaler *scaler =
-		&crtc_state->scaler_state.scalers[plane_state->scaler_id];
 
 	plane_ctl = PLANE_CTL_ENABLE |
 		PLANE_CTL_PIPE_GAMMA_ENABLE |
@@ -262,10 +260,14 @@ skl_update_plane(struct drm_plane *drm_plane,
 	if (plane_state->scaler_id >= 0) {
 		uint32_t ps_ctrl = 0;
 		int scaler_id = plane_state->scaler_id;
+		const struct intel_scaler *scaler;
 
 		DRM_DEBUG_KMS("plane = %d PS_PLANE_SEL(plane) = 0x%x\n", plane,
 			PS_PLANE_SEL(plane));
+
+		scaler = &crtc_state->scaler_state.scalers[scaler_id];
 		ps_ctrl = PS_SCALER_EN | PS_PLANE_SEL(plane) | scaler->mode;
+
 		I915_WRITE(SKL_PS_CTRL(pipe, scaler_id), ps_ctrl);
 		I915_WRITE(SKL_PS_PWR_GATE(pipe, scaler_id), 0);
 		I915_WRITE(SKL_PS_WIN_POS(pipe, scaler_id), (crtc_x << 16) | crtc_y);
-- 
2.5.0