[PATCH v13 5/6] drm/mediatek: dpi sample mode support

[Jitao Shi <jitao.shi@xxxxxxxxxxxx>]

DPI can sample on falling, rising or both edge.
When DPI sample the data both rising and falling edge.
It can reduce half data io pins.

Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>
Signed-off-by: Jitao Shi <jitao.shi@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_dpi.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
index 087f5ce732e1..2871e68e7767 100644
--- a/drivers/gpu/drm/mediatek/mtk_dpi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
@@ -75,6 +75,7 @@ struct mtk_dpi {
 	enum mtk_dpi_out_bit_num bit_num;
 	enum mtk_dpi_out_channel_swap channel_swap;
 	int refcount;
+	u32 pclk_sample;
 };
 
 static inline struct mtk_dpi *mtk_dpi_from_encoder(struct drm_encoder *e)
@@ -348,6 +349,13 @@ static void mtk_dpi_config_disable_edge(struct mtk_dpi *dpi)
 		mtk_dpi_mask(dpi, dpi->conf->reg_h_fre_con, 0, EDGE_SEL_EN);
 }
 
+static void mtk_dpi_enable_pclk_sample_dual_edge(struct mtk_dpi *dpi)
+{
+	mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN | DDR_4PHASE,
+		     DDR_EN | DDR_4PHASE);
+	mtk_dpi_mask(dpi, DPI_OUTPUT_SETTING, EDGE_SEL, EDGE_SEL);
+}
+
 static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
 					enum mtk_dpi_out_color_format format)
 {
@@ -439,7 +447,8 @@ 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);
+	clk_set_rate(dpi->pixel_clk,
+		     vm.pixelclock * (dpi->pclk_sample > 1 ? 2 : 1));
 	vm.pixelclock = clk_get_rate(dpi->pixel_clk);
 
 	dev_dbg(dpi->dev, "Got  PLL %lu Hz, pixel clock %lu Hz\n",
@@ -450,7 +459,8 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
 	limit.y_bottom = 0x0010;
 	limit.y_top = 0x0FE0;
 
-	dpi_pol.ck_pol = MTK_DPI_POLARITY_FALLING;
+	dpi_pol.ck_pol = dpi->pclk_sample == 1 ?
+			 MTK_DPI_POLARITY_RISING : MTK_DPI_POLARITY_FALLING;
 	dpi_pol.de_pol = MTK_DPI_POLARITY_RISING;
 	dpi_pol.hsync_pol = vm.flags & DISPLAY_FLAGS_HSYNC_HIGH ?
 			    MTK_DPI_POLARITY_FALLING : MTK_DPI_POLARITY_RISING;
@@ -504,6 +514,8 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
 	mtk_dpi_config_color_format(dpi, dpi->color_format);
 	mtk_dpi_config_2n_h_fre(dpi);
 	mtk_dpi_config_disable_edge(dpi);
+	if (dpi->pclk_sample > 1)
+		mtk_dpi_enable_pclk_sample_dual_edge(dpi);
 	mtk_dpi_sw_reset(dpi, false);
 
 	return 0;
@@ -693,6 +705,7 @@ static const struct mtk_dpi_conf mt8183_conf = {
 static int mtk_dpi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct device_node *ep;
 	struct mtk_dpi *dpi;
 	struct resource *mem;
 	int comp_id;
@@ -705,6 +718,16 @@ static int mtk_dpi_probe(struct platform_device *pdev)
 	dpi->dev = dev;
 	dpi->conf = (struct mtk_dpi_conf *)of_device_get_match_data(dev);
 
+	ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
+	if (!ep) {
+		dev_err(dev, "Failed get the endpoint port\n");
+		return -EINVAL;
+	}
+
+	/* Get the sampling edge from the endpoint. */
+	of_property_read_u32(ep, "pclk-sample", &dpi->pclk_sample);
+	of_node_put(ep);
+
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	dpi->regs = devm_ioremap_resource(dev, mem);
 	if (IS_ERR(dpi->regs)) {
-- 
2.21.0