drm/msm/dpu: Introduce PINGPONG_NONE to disconnect DSC from PINGPONG

Disabling the crossbar mux between DSC and PINGPONG currently
requires a bogus enum dpu_pingpong value to be passed when calling
dsc_bind_pingpong_blk() with enable=false, even though the register
value written is independent of the current PINGPONG block.  Replace
that `bool enable` parameter with a new PINGPONG_NONE dpu_pingpong
flag that triggers the write of the "special" 0xF "crossbar
disabled" value to the register instead.

Changes in v4:
-- more details to commit text

Changes in v5:
-- rewording commit text suggested by Marijn
-- add DRM_DEBUG_KMS for DSC unbinding case

Changes in v8:
-- fix checkpatch warning
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/539505/
Link: https://lore.kernel.org/r/1685036458-22683-6-git-send-email-quic_khsieh@quicinc.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

@@ -1850,7 +1850,7 @@ static void dpu_encoder_dsc_pipe_cfg(struct dpu_hw_dsc *hw_dsc,
 		hw_pp->ops.setup_dsc(hw_pp);
 
 	if (hw_dsc->ops.dsc_bind_pingpong_blk)
-		hw_dsc->ops.dsc_bind_pingpong_blk(hw_dsc, true, hw_pp->idx);
+		hw_dsc->ops.dsc_bind_pingpong_blk(hw_dsc, hw_pp->idx);
 
 	if (hw_pp->ops.enable_dsc)
 		hw_pp->ops.enable_dsc(hw_pp);

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c

@@ -154,7 +154,6 @@ static void dpu_hw_dsc_config_thresh(struct dpu_hw_dsc *hw_dsc,
 
 static void dpu_hw_dsc_bind_pingpong_blk(
 		struct dpu_hw_dsc *hw_dsc,
-		bool enable,
 		const enum dpu_pingpong pp)
 {
 	struct dpu_hw_blk_reg_map *c = &hw_dsc->hw;
@@ -163,14 +162,15 @@ static void dpu_hw_dsc_bind_pingpong_blk(
 
 	dsc_ctl_offset = DSC_CTL(hw_dsc->idx);
 
-	if (enable)
+	if (pp)
 		mux_cfg = (pp - PINGPONG_0) & 0x7;
 
-	DRM_DEBUG_KMS("%s dsc:%d %s pp:%d\n",
-			enable ? "Binding" : "Unbinding",
-			hw_dsc->idx - DSC_0,
-			enable ? "to" : "from",
-			pp - PINGPONG_0);
+	if (pp)
+		DRM_DEBUG_KMS("Binding dsc:%d to pp:%d\n",
+			      hw_dsc->idx - DSC_0, pp - PINGPONG_0);
+	else
+		DRM_DEBUG_KMS("Unbinding dsc:%d from any pp\n",
+			      hw_dsc->idx - DSC_0);
 
 	DPU_REG_WRITE(c, dsc_ctl_offset, mux_cfg);
 }

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h

@@ -44,7 +44,6 @@ struct dpu_hw_dsc_ops {
 				  struct drm_dsc_config *dsc);
 
 	void (*dsc_bind_pingpong_blk)(struct dpu_hw_dsc *hw_dsc,
-				  bool enable,
 				  enum dpu_pingpong pp);
 };