[PATCH 38/40] drm/rockchip: pre dither down when output bpc is 8bit

[Thierry Escande]

From: Mark Yao <mark.yao at rock-chips.com>

Some encoder have a crc verification check, crc check fail if
input and output data is not equal.

That means encoder input and output need use same color depth,
vop can output 10bit data to encoder, but some panel only support
8bit depth, that would make crc check die.

So pre dither down vop data to 8bit if panel's bpc is 8.

Signed-off-by: Mark Yao <mark.yao at rock-chips.com>
[seanpaul resolved conflict in rockchip_drm_vop.c]
Signed-off-by: Sean Paul <seanpaul at chromium.org>
Signed-off-by: Thierry Escande <thierry.escande at collabora.com>
---
 drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 2 ++
 drivers/gpu/drm/rockchip/rockchip_drm_drv.h     | 1 +
 drivers/gpu/drm/rockchip/rockchip_drm_vop.c     | 6 ++++++
 drivers/gpu/drm/rockchip/rockchip_drm_vop.h     | 1 +
 drivers/gpu/drm/rockchip/rockchip_vop_reg.c     | 1 +
 5 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
index bd2ff2c429e9..a6a3d6f1f127 100644
--- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
@@ -218,6 +218,7 @@ rockchip_dp_drm_encoder_atomic_check(struct drm_encoder *encoder,
 				      struct drm_connector_state *conn_state)
 {
 	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
+	struct drm_display_info *di = &conn_state->connector->display_info;
 
 	/*
 	 * The hardware IC designed that VOP must output the RGB10 video
@@ -229,6 +230,7 @@ rockchip_dp_drm_encoder_atomic_check(struct drm_encoder *encoder,
 
 	s->output_mode = ROCKCHIP_OUT_MODE_AAAA;
 	s->output_type = DRM_MODE_CONNECTOR_eDP;
+	s->output_bpc = di->bpc;
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
index 9c064a40458b..3a6ebfc26036 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
@@ -36,6 +36,7 @@ struct rockchip_crtc_state {
 	struct drm_crtc_state base;
 	int output_type;
 	int output_mode;
+	int output_bpc;
 };
 #define to_rockchip_crtc_state(s) \
 		container_of(s, struct rockchip_crtc_state, base)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index ba9913961273..8c11a4dc436e 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -937,6 +937,12 @@ static void vop_crtc_atomic_enable(struct drm_crtc *crtc,
 	if (s->output_mode == ROCKCHIP_OUT_MODE_AAAA &&
 	    !(vop_data->feature & VOP_FEATURE_OUTPUT_RGB10))
 		s->output_mode = ROCKCHIP_OUT_MODE_P888;
+
+	if (s->output_mode == ROCKCHIP_OUT_MODE_AAAA && s->output_bpc == 8)
+		VOP_REG_SET(vop, common, pre_dither_down, 1);
+	else
+		VOP_REG_SET(vop, common, pre_dither_down, 0);
+
 	VOP_REG_SET(vop, common, out_mode, s->output_mode);
 
 	VOP_REG_SET(vop, modeset, htotal_pw, (htotal << 16) | hsync_len);
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
index 56bbd2e2a8ef..084acdd0019a 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
@@ -67,6 +67,7 @@ struct vop_common {
 	struct vop_reg cfg_done;
 	struct vop_reg dsp_blank;
 	struct vop_reg data_blank;
+	struct vop_reg pre_dither_down;
 	struct vop_reg dither_down;
 	struct vop_reg dither_up;
 	struct vop_reg gate_en;
diff --git a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
index 2e4eea3459fe..08023d3ecb76 100644
--- a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
+++ b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
@@ -264,6 +264,7 @@ static const struct vop_common rk3288_common = {
 	.standby = VOP_REG_SYNC(RK3288_SYS_CTRL, 0x1, 22),
 	.gate_en = VOP_REG(RK3288_SYS_CTRL, 0x1, 23),
 	.mmu_en = VOP_REG(RK3288_SYS_CTRL, 0x1, 20),
+	.pre_dither_down = VOP_REG(RK3288_DSP_CTRL1, 0x1, 1),
 	.dither_down = VOP_REG(RK3288_DSP_CTRL1, 0xf, 1),
 	.dither_up = VOP_REG(RK3288_DSP_CTRL1, 0x1, 6),
 	.data_blank = VOP_REG(RK3288_DSP_CTRL0, 0x1, 19),
-- 
2.14.1