RP1 DPI: Add interlaced modes

arch/arm/boot/dts/overlays/README

@@ -5099,6 +5099,7 @@ Params: clock-frequency         Display clock frequency (Hz)
         vsync-invert            Vertical sync active low
         de-invert               Data Enable active low
         pixclk-invert           Negative edge pixel clock
+        interlaced              Use an interlaced mode (where supported)
         width-mm                Define the screen width in mm
         height-mm               Define the screen height in mm
         rgb565                  Change to RGB565 output on GPIOs 0-19

arch/arm/boot/dts/overlays/vc4-kms-dpi-generic-overlay.dts

@@ -59,6 +59,7 @@
 		vsync-invert = <&timing>, "vsync-active:0=0";
 		de-invert = <&timing>, "de-active:0=0";
 		pixclk-invert = <&timing>, "pixelclk-active:0=0";
+		interlaced = <&timing>, "interlaced?";
 
 		width-mm = <&panel_generic>, "width-mm:0";
 		height-mm = <&panel_generic>, "height-mm:0";

drivers/gpu/drm/bridge/panel.c

@@ -82,6 +82,8 @@ static int panel_bridge_attach(struct drm_bridge *bridge,
 		return ret;
 	}
 
+	connector->interlace_allowed = true;
+
 	drm_panel_bridge_set_orientation(connector, bridge);
 
 	drm_connector_attach_encoder(&panel_bridge->connector,

drivers/gpu/drm/rp1/rp1-dpi/Makefile

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-drm-rp1-dpi-y := rp1_dpi.o rp1_dpi_hw.o rp1_dpi_cfg.o
+drm-rp1-dpi-y := rp1_dpi.o rp1_dpi_hw.o rp1_dpi_cfg.o rp1_dpi_pio.o
 
 obj-$(CONFIG_DRM_RP1_DPI) += drm-rp1-dpi.o

drivers/gpu/drm/rp1/rp1-dpi/rp1_dpi.c

@@ -80,6 +80,7 @@ static void rp1dpi_pipe_update(struct drm_simple_display_pipe *pipe,
 			if (dpi->dpi_running &&
 			    fb->format->format != dpi->cur_fmt) {
 				rp1dpi_hw_stop(dpi);
+				rp1dpi_pio_stop(dpi);
 				dpi->dpi_running = false;
 			}
 			if (!dpi->dpi_running) {
@@ -88,6 +89,7 @@ static void rp1dpi_pipe_update(struct drm_simple_display_pipe *pipe,
 						dpi->bus_fmt,
 						dpi->de_inv,
 						&pipe->crtc.state->mode);
+				rp1dpi_pio_start(dpi, &pipe->crtc.state->mode);
 				dpi->dpi_running = true;
 			}
 			dpi->cur_fmt = fb->format->format;
@@ -187,6 +189,7 @@ static void rp1dpi_pipe_disable(struct drm_simple_display_pipe *pipe)
 	drm_crtc_vblank_off(&pipe->crtc);
 	if (dpi->dpi_running) {
 		rp1dpi_hw_stop(dpi);
+		rp1dpi_pio_stop(dpi);
 		dpi->dpi_running = false;
 	}
 	clk_disable_unprepare(dpi->clocks[RP1DPI_CLK_DPI]);
@@ -236,6 +239,7 @@ static void rp1dpi_stopall(struct drm_device *drm)
 		if (dpi->dpi_running || rp1dpi_hw_busy(dpi)) {
 			rp1dpi_hw_stop(dpi);
 			clk_disable_unprepare(dpi->clocks[RP1DPI_CLK_DPI]);
+			rp1dpi_pio_stop(dpi);
 			dpi->dpi_running = false;
 		}
 		rp1dpi_vidout_poweroff(dpi);
@@ -273,7 +277,7 @@ static int rp1dpi_platform_probe(struct platform_device *pdev)
 	struct rp1_dpi *dpi;
 	struct drm_bridge *bridge = NULL;
 	struct drm_panel *panel;
-	int i, ret;
+	int i, j, ret;
 
 	dev_info(dev, __func__);
 	ret = drm_of_find_panel_or_bridge(pdev->dev.of_node, 0, 0,
@@ -295,6 +299,7 @@ static int rp1dpi_platform_probe(struct platform_device *pdev)
 		return ret;
 	}
 	dpi->pdev = pdev;
+	spin_lock_init(&dpi->hw_lock);
 
 	dpi->bus_fmt = default_bus_fmt;
 	ret = of_property_read_u32(dev->of_node, "default_bus_fmt", &dpi->bus_fmt);
@@ -332,6 +337,33 @@ static int rp1dpi_platform_probe(struct platform_device *pdev)
 	if (ret)
 		goto done_err;
 
+	/* Check if PIO can snoop on or override DPI's GPIO1 */
+	dpi->gpio1_used = false;
+	for (i = 0; !dpi->gpio1_used; i++) {
+		u32 p = 0;
+		const char *str = NULL;
+		struct device_node *np1 = of_parse_phandle(dev->of_node, "pinctrl-0", i);
+
+		if (!np1)
+			break;
+
+		if (!of_property_read_string(np1, "function", &str) && !strcmp(str, "dpi")) {
+			for (j = 0; !dpi->gpio1_used; j++) {
+				if (of_property_read_string_index(np1, "pins", j, &str))
+					break;
+				if (!strcmp(str, "gpio1"))
+					dpi->gpio1_used = true;
+			}
+			for (j = 0; !dpi->gpio1_used; j++) {
+				if (of_property_read_u32_index(np1, "brcm,pins", j, &p))
+					break;
+				if (p == 1)
+					dpi->gpio1_used = true;
+			}
+		}
+		of_node_put(np1);
+	}
+
 	/* Now we have all our resources, finish driver initialization */
 	dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
 	init_completion(&dpi->finished);

drivers/gpu/drm/rp1/rp1-dpi/rp1_dpi.h

@@ -46,6 +46,18 @@ struct rp1_dpi {
 	bool de_inv, clk_inv;
 	bool dpi_running, pipe_enabled;
 	struct completion finished;
+
+	/* Experimental stuff for interlace follows */
+	struct rp1_pio_client *pio;
+	bool gpio1_used;
+	bool pio_stole_gpio2;
+
+	spinlock_t hw_lock; /* the following are used in line-match ISR */
+	dma_addr_t last_dma_addr;
+	u32 last_stride;
+	u32 shorter_front_porch;
+	bool interlaced;
+	bool lower_field_flag;
 };
 
 /* ---------------------------------------------------------------------- */
@@ -67,3 +79,9 @@ void rp1dpi_hw_vblank_ctrl(struct rp1_dpi *dpi, int enable);
 
 void rp1dpi_vidout_setup(struct rp1_dpi *dpi, bool drive_negedge);
 void rp1dpi_vidout_poweroff(struct rp1_dpi *dpi);
+
+/* ---------------------------------------------------------------------- */
+/* PIO control -- we need PIO to generate VSync (from DE) when interlaced */
+
+int rp1dpi_pio_start(struct rp1_dpi *dpi, const struct drm_display_mode *mode);
+void rp1dpi_pio_stop(struct rp1_dpi *dpi);