drm/mediatek: add gmc_bits for ovl private data

This patch add gmc_bits for ovl private data
GMC register was set RDMA ultra and pre-ultra threshold.
10bit GMC register define is different with other SOC, gmc_thrshd_l not
used.
Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>

drivers/gpu/drm/mediatek/mtk_disp_ovl.c

@@ -31,7 +31,9 @@
 #define DISP_REG_OVL_ADDR_MT8173		0x0f40
 #define DISP_REG_OVL_ADDR(ovl, n)		((ovl)->data->addr + 0x20 * (n))
 
-#define	OVL_RDMA_MEM_GMC	0x40402020
+#define GMC_THRESHOLD_BITS	16
+#define GMC_THRESHOLD_HIGH	((1 << GMC_THRESHOLD_BITS) / 4)
+#define GMC_THRESHOLD_LOW	((1 << GMC_THRESHOLD_BITS) / 8)
 
 #define OVL_CON_BYTE_SWAP	BIT(24)
 #define OVL_CON_MTX_YUV_TO_RGB	(6 << 16)
@@ -49,6 +51,7 @@
 
 struct mtk_disp_ovl_data {
 	unsigned int addr;
+	unsigned int gmc_bits;
 	bool fmt_rgb565_is_0;
 };
 
@@ -132,9 +135,23 @@ static unsigned int mtk_ovl_layer_nr(struct mtk_ddp_comp *comp)
 static void mtk_ovl_layer_on(struct mtk_ddp_comp *comp, unsigned int idx)
 {
 	unsigned int reg;
+	unsigned int gmc_thrshd_l;
+	unsigned int gmc_thrshd_h;
+	unsigned int gmc_value;
+	struct mtk_disp_ovl *ovl = comp_to_ovl(comp);
 
 	writel(0x1, comp->regs + DISP_REG_OVL_RDMA_CTRL(idx));
-	writel(OVL_RDMA_MEM_GMC, comp->regs + DISP_REG_OVL_RDMA_GMC(idx));
+
+	gmc_thrshd_l = GMC_THRESHOLD_LOW >>
+		      (GMC_THRESHOLD_BITS - ovl->data->gmc_bits);
+	gmc_thrshd_h = GMC_THRESHOLD_HIGH >>
+		      (GMC_THRESHOLD_BITS - ovl->data->gmc_bits);
+	if (ovl->data->gmc_bits == 10)
+		gmc_value = gmc_thrshd_h | gmc_thrshd_h << 16;
+	else
+		gmc_value = gmc_thrshd_l | gmc_thrshd_l << 8 |
+			    gmc_thrshd_h << 16 | gmc_thrshd_h << 24;
+	writel(gmc_value, comp->regs + DISP_REG_OVL_RDMA_GMC(idx));
 
 	reg = readl(comp->regs + DISP_REG_OVL_SRC_CON);
 	reg = reg | BIT(idx);
@@ -316,11 +333,13 @@ static int mtk_disp_ovl_remove(struct platform_device *pdev)
 
 static const struct mtk_disp_ovl_data mt2701_ovl_driver_data = {
 	.addr = DISP_REG_OVL_ADDR_MT2701,
+	.gmc_bits = 8,
 	.fmt_rgb565_is_0 = false,
 };
 
 static const struct mtk_disp_ovl_data mt8173_ovl_driver_data = {
 	.addr = DISP_REG_OVL_ADDR_MT8173,
+	.gmc_bits = 8,
 	.fmt_rgb565_is_0 = true,
 };