drm/i915/gen9: Avoid using negative array index in skl_update_plane()

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.

v2:
- Remove ps_ctrl while at it (Ville).

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463059132-1720-2-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 0f3e2303e0e9b08229d29a7cc47172bf0efbeef5..57eef129c597e9804ea87f13f365d94f5e86ec6b 100644 (file)
--- 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 |
@@ -260,13 +258,16 @@ skl_update_plane(struct drm_plane *drm_plane,
 
        /* program plane scaler */
        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));
-               ps_ctrl = PS_SCALER_EN | PS_PLANE_SEL(plane) | scaler->mode;
-               I915_WRITE(SKL_PS_CTRL(pipe, scaler_id), ps_ctrl);
+
+               scaler = &crtc_state->scaler_state.scalers[scaler_id];
+
+               I915_WRITE(SKL_PS_CTRL(pipe, scaler_id),
+                          PS_SCALER_EN | PS_PLANE_SEL(plane) | scaler->mode);
                I915_WRITE(SKL_PS_PWR_GATE(pipe, scaler_id), 0);
                I915_WRITE(SKL_PS_WIN_POS(pipe, scaler_id), (crtc_x << 16) | crtc_y);
                I915_WRITE(SKL_PS_WIN_SZ(pipe, scaler_id),