drm/tegra: dc: Implement hardware VBLANK counter

The display controller on Tegra can use syncpoints to count VBLANK
events. syncpoints are 32-bit unsigned integers, so well suited as
VBLANK counters.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/dc.c

@@ -906,6 +906,15 @@ static int tegra_dc_add_planes(struct drm_device *drm, struct tegra_dc *dc)
 	return 0;
 }
 
+u32 tegra_dc_get_vblank_counter(struct tegra_dc *dc)
+{
+	if (dc->syncpt)
+		return host1x_syncpt_read(dc->syncpt);
+
+	/* fallback to software emulated VBLANK counter */
+	return drm_crtc_vblank_count(&dc->base);
+}
+
 void tegra_dc_enable_vblank(struct tegra_dc *dc)
 {
 	unsigned long value, flags;
@@ -1632,7 +1641,6 @@ static int tegra_dc_init(struct host1x_client *client)
 	struct tegra_drm *tegra = drm->dev_private;
 	struct drm_plane *primary = NULL;
 	struct drm_plane *cursor = NULL;
-	unsigned int syncpt;
 	u32 value;
 	int err;
 
@@ -1701,13 +1709,15 @@ static int tegra_dc_init(struct host1x_client *client)
 	}
 
 	/* initialize display controller */
-	if (dc->pipe)
-		syncpt = SYNCPT_VBLANK1;
-	else
-		syncpt = SYNCPT_VBLANK0;
+	if (dc->syncpt) {
+		u32 syncpt = host1x_syncpt_id(dc->syncpt);
 
-	tegra_dc_writel(dc, 0x00000100, DC_CMD_GENERAL_INCR_SYNCPT_CNTRL);
-	tegra_dc_writel(dc, 0x100 | syncpt, DC_CMD_CONT_SYNCPT_VSYNC);
+		value = SYNCPT_CNTRL_NO_STALL;
+		tegra_dc_writel(dc, value, DC_CMD_GENERAL_INCR_SYNCPT_CNTRL);
+
+		value = SYNCPT_VSYNC_ENABLE | syncpt;
+		tegra_dc_writel(dc, value, DC_CMD_CONT_SYNCPT_VSYNC);
+	}
 
 	value = WIN_A_UF_INT | WIN_B_UF_INT | WIN_C_UF_INT | WIN_A_OF_INT;
 	tegra_dc_writel(dc, value, DC_CMD_INT_TYPE);
@@ -1875,6 +1885,7 @@ static int tegra_dc_parse_dt(struct tegra_dc *dc)
 
 static int tegra_dc_probe(struct platform_device *pdev)
 {
+	unsigned long flags = HOST1X_SYNCPT_CLIENT_MANAGED;
 	const struct of_device_id *id;
 	struct resource *regs;
 	struct tegra_dc *dc;
@@ -1966,6 +1977,10 @@ static int tegra_dc_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	dc->syncpt = host1x_syncpt_request(&pdev->dev, flags);
+	if (!dc->syncpt)
+		dev_warn(&pdev->dev, "failed to allocate syncpoint\n");
+
 	platform_set_drvdata(pdev, dc);
 
 	return 0;
@@ -1976,6 +1991,8 @@ static int tegra_dc_remove(struct platform_device *pdev)
 	struct tegra_dc *dc = platform_get_drvdata(pdev);
 	int err;
 
+	host1x_syncpt_free(dc->syncpt);
+
 	err = host1x_client_unregister(&dc->client);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to unregister host1x client: %d\n",

drivers/gpu/drm/tegra/dc.h

@@ -12,6 +12,8 @@
 
 #define DC_CMD_GENERAL_INCR_SYNCPT		0x000
 #define DC_CMD_GENERAL_INCR_SYNCPT_CNTRL	0x001
+#define  SYNCPT_CNTRL_NO_STALL   (1 << 8)
+#define  SYNCPT_CNTRL_SOFT_RESET (1 << 0)
 #define DC_CMD_GENERAL_INCR_SYNCPT_ERROR	0x002
 #define DC_CMD_WIN_A_INCR_SYNCPT		0x008
 #define DC_CMD_WIN_A_INCR_SYNCPT_CNTRL		0x009
@@ -23,6 +25,7 @@
 #define DC_CMD_WIN_C_INCR_SYNCPT_CNTRL		0x019
 #define DC_CMD_WIN_C_INCR_SYNCPT_ERROR		0x01a
 #define DC_CMD_CONT_SYNCPT_VSYNC		0x028
+#define  SYNCPT_VSYNC_ENABLE (1 << 8)
 #define DC_CMD_DISPLAY_COMMAND_OPTION0		0x031
 #define DC_CMD_DISPLAY_COMMAND			0x032
 #define DISP_CTRL_MODE_STOP (0 << 5)
@@ -438,8 +441,4 @@
 #define DC_WINBUF_BD_UFLOW_STATUS		0xdca
 #define DC_WINBUF_CD_UFLOW_STATUS		0xfca
 
-/* synchronization points */
-#define SYNCPT_VBLANK0 26
-#define SYNCPT_VBLANK1 27
-
 #endif /* TEGRA_DC_H */

drivers/gpu/drm/tegra/drm.c

@@ -172,6 +172,10 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 	 */
 	drm->irq_enabled = true;
 
+	/* syncpoints are used for full 32-bit hardware VBLANK counters */
+	drm->vblank_disable_immediate = true;
+	drm->max_vblank_count = 0xffffffff;
+
 	err = drm_vblank_init(drm, drm->mode_config.num_crtc);
 	if (err < 0)
 		goto device;
@@ -813,12 +817,12 @@ static struct drm_crtc *tegra_crtc_from_pipe(struct drm_device *drm,
 static u32 tegra_drm_get_vblank_counter(struct drm_device *drm, int pipe)
 {
 	struct drm_crtc *crtc = tegra_crtc_from_pipe(drm, pipe);
+	struct tegra_dc *dc = to_tegra_dc(crtc);
 
 	if (!crtc)
 		return 0;
 
-	/* TODO: implement real hardware counter using syncpoints */
-	return drm_crtc_vblank_count(crtc);
+	return tegra_dc_get_vblank_counter(dc);
 }
 
 static int tegra_drm_enable_vblank(struct drm_device *drm, int pipe)

drivers/gpu/drm/tegra/drm.h

@@ -106,6 +106,7 @@ struct tegra_output;
 
 struct tegra_dc {
 	struct host1x_client client;
+	struct host1x_syncpt *syncpt;
 	struct device *dev;
 	spinlock_t lock;
 
@@ -180,6 +181,7 @@ struct tegra_dc_window {
 };
 
 /* from dc.c */
+u32 tegra_dc_get_vblank_counter(struct tegra_dc *dc);
 void tegra_dc_enable_vblank(struct tegra_dc *dc);
 void tegra_dc_disable_vblank(struct tegra_dc *dc);
 void tegra_dc_cancel_page_flip(struct drm_crtc *crtc, struct drm_file *file);