drm/mediatek: Add has_dither private data for gamma

Not all SoC has dither function in gamma module.
Add private data to control this function setting.
Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_disp_gamma.c

@@ -26,7 +26,7 @@
 #define LUT_10BIT_MASK				0x03ff
 
 struct mtk_disp_gamma_data {
-	u32 reserved;
+	bool has_dither;
 };
 
 /**
@@ -92,8 +92,9 @@ void mtk_gamma_config(struct device *dev, unsigned int w,
 
 	mtk_ddp_write(cmdq_pkt, h << 16 | w, &gamma->cmdq_reg, gamma->regs,
 		      DISP_GAMMA_SIZE);
-	mtk_dither_set_common(gamma->regs, &gamma->cmdq_reg, bpc, DISP_GAMMA_CFG,
-			      GAMMA_DITHERING, cmdq_pkt);
+	if (gamma->data && gamma->data->has_dither)
+		mtk_dither_set_common(gamma->regs, &gamma->cmdq_reg, bpc,
+				      DISP_GAMMA_CFG, GAMMA_DITHERING, cmdq_pkt);
 }
 
 void mtk_gamma_start(struct device *dev)
@@ -173,8 +174,13 @@ static int mtk_disp_gamma_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct mtk_disp_gamma_data mt8173_gamma_driver_data = {
+	.has_dither = true,
+};
+
 static const struct of_device_id mtk_disp_gamma_driver_dt_match[] = {
-	{ .compatible = "mediatek,mt8173-disp-gamma"},
+	{ .compatible = "mediatek,mt8173-disp-gamma",
+	  .data = &mt8173_gamma_driver_data},
 	{},
 };
 MODULE_DEVICE_TABLE(of, mtk_disp_gamma_driver_dt_match);