drm/mediatek: dpi: Add dual edge sample mode support

To support RGB888_2X12_LE and RGB888_2X12_BE, dpi should sample
on dual edge which could recude half data io pins.
For RGB888_1X24, dpi just sample on single edge (rising or falling
edge).
Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_dpi.c

@@ -83,6 +83,7 @@ struct mtk_dpi {
 	struct pinctrl *pinctrl;
 	struct pinctrl_state *pins_gpio;
 	struct pinctrl_state *pins_dpi;
+	u32 output_fmt;
 	int refcount;
 };
 
@@ -381,6 +382,20 @@ static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
 	}
 }
 
+static void mtk_dpi_dual_edge(struct mtk_dpi *dpi)
+{
+	if ((dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_LE) ||
+	    (dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_BE)) {
+		mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN | DDR_4PHASE,
+			     DDR_EN | DDR_4PHASE);
+		mtk_dpi_mask(dpi, DPI_OUTPUT_SETTING,
+			     dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_LE ?
+			     EDGE_SEL : 0, EDGE_SEL);
+	} else {
+		mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN | DDR_4PHASE, 0);
+	}
+}
+
 static void mtk_dpi_power_off(struct mtk_dpi *dpi)
 {
 	if (WARN_ON(dpi->refcount == 0))
@@ -455,7 +470,13 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
 	pll_rate = clk_get_rate(dpi->tvd_clk);
 
 	vm.pixelclock = pll_rate / factor;
-	clk_set_rate(dpi->pixel_clk, vm.pixelclock);
+	if ((dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_LE) ||
+	    (dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_BE))
+		clk_set_rate(dpi->pixel_clk, vm.pixelclock * 2);
+	else
+		clk_set_rate(dpi->pixel_clk, vm.pixelclock);
+
+
 	vm.pixelclock = clk_get_rate(dpi->pixel_clk);
 
 	dev_dbg(dpi->dev, "Got  PLL %lu Hz, pixel clock %lu Hz\n",
@@ -519,6 +540,7 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
 	mtk_dpi_config_yc_map(dpi, dpi->yc_map);
 	mtk_dpi_config_color_format(dpi, dpi->color_format);
 	mtk_dpi_config_2n_h_fre(dpi);
+	mtk_dpi_dual_edge(dpi);
 	mtk_dpi_config_disable_edge(dpi);
 	mtk_dpi_sw_reset(dpi, false);
 
@@ -718,6 +740,7 @@ static int mtk_dpi_probe(struct platform_device *pdev)
 
 	dpi->dev = dev;
 	dpi->conf = (struct mtk_dpi_conf *)of_device_get_match_data(dev);
+	dpi->output_fmt = MEDIA_BUS_FMT_RGB888_1X24;
 
 	dpi->pinctrl = devm_pinctrl_get(&pdev->dev);
 	if (IS_ERR(dpi->pinctrl)) {