drm/msm/mdp5: Prepare CRTC/LM for empty stages

Use SSPP_NONE in mdp5_plane_pipe() if there is now hwpipe allocated for
the drm_plane. Returning '0' means we are returning VIG0 pipe.

Also, use the mdp5_pipe enum to pass around the stage array. Initialize
the stage to SSPP_NONE by default.

We do the above because 1) Cursor plane has to be staged at the topmost
blender of the LM, which can result in empty stages in between 2) In
the future, when we support multiple LMs per CRTC. We could have stages
which don't have any pipe assigned to them.
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/mdp/mdp5/mdp5_crtc.c

@@ -195,7 +195,7 @@ static void blend_setup(struct drm_crtc *crtc)
 	uint32_t lm = mdp5_crtc->lm;
 	uint32_t blend_op, fg_alpha, bg_alpha, ctl_blend_flags = 0;
 	unsigned long flags;
-	uint8_t stage[STAGE_MAX + 1];
+	enum mdp5_pipe stage[STAGE_MAX + 1] = { SSPP_NONE };
 	int i, plane_cnt = 0;
 #define blender(stage)	((stage) - STAGE0)
 

drivers/gpu/drm/msm/mdp/mdp5/mdp5_ctl.c

@@ -351,7 +351,7 @@ static u32 mdp_ctl_blend_ext_mask(enum mdp5_pipe pipe,
 	}
 }
 
-int mdp5_ctl_blend(struct mdp5_ctl *ctl, u8 *stage, u32 stage_cnt,
+int mdp5_ctl_blend(struct mdp5_ctl *ctl, enum mdp5_pipe *stage, u32 stage_cnt,
 		   u32 ctl_blend_op_flags)
 {
 	unsigned long flags;

drivers/gpu/drm/msm/mdp/mdp5/mdp5_ctl.h

@@ -56,7 +56,7 @@ int mdp5_ctl_pair(struct mdp5_ctl *ctlx, struct mdp5_ctl *ctly, bool enable);
  * (call mdp5_ctl_commit() with mdp_ctl_flush_mask_ctl() mask)
  */
 #define MDP5_CTL_BLEND_OP_FLAG_BORDER_OUT	BIT(0)
-int mdp5_ctl_blend(struct mdp5_ctl *ctl, u8 *stage, u32 stage_cnt,
+int mdp5_ctl_blend(struct mdp5_ctl *ctl, enum mdp5_pipe *stage, u32 stage_cnt,
 		   u32 ctl_blend_op_flags);
 
 /**

drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c

@@ -823,7 +823,7 @@ enum mdp5_pipe mdp5_plane_pipe(struct drm_plane *plane)
 	struct mdp5_plane_state *pstate = to_mdp5_plane_state(plane->state);
 
 	if (WARN_ON(!pstate->hwpipe))
-		return 0;
+		return SSPP_NONE;
 
 	return pstate->hwpipe->pipe;
 }