Tested to fix banding on the 6-bit panel of the ASUS C201.
Signed-off-by: Urja Rannikko <urjaman@xxxxxxxxx>
---
drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index 0c35a88e33dd..96ba1b4cd07b 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -896,6 +896,7 @@ static void vop_crtc_atomic_enable(struct drm_crtc *crtc,
u16 vsync_len = adjusted_mode->vsync_end - adjusted_mode->vsync_start;
u16 vact_st = adjusted_mode->vtotal - adjusted_mode->vsync_start;
u16 vact_end = vact_st + vdisplay;
+ uint32_t dither_bits = 0;
uint32_t pin_pol, val;
int ret;
@@ -951,10 +952,15 @@ static void vop_crtc_atomic_enable(struct drm_crtc *crtc,
!(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);
+ /* dither_down includes the bit for pre_dither_down */
+ if (s->output_bpc) { /* Only dither if bpc known. */
+ if (s->output_mode == ROCKCHIP_OUT_MODE_AAAA && s->output_bpc <= 8)
+ dither_bits = 0x1;
+ /* Enable allegro dither to RGB666 */
+ if (s->output_bpc == 6)
+ dither_bits |= 0x6;
+ }
+ VOP_REG_SET(vop, common, dither_down, dither_bits);
VOP_REG_SET(vop, common, out_mode, s->output_mode);
--
2.20.1
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