Re: [PATCH v4 4/6] drm/sprd: add Unisoc's drm display controller driver

Hi,

On Mon, Feb 22, 2021 at 09:28:20PM +0800, Kevin Tang wrote:

Adds DPU(Display Processor Unit) support for the Unisoc's display subsystem.
It's support multi planes, scaler, rotation, PQ(Picture Quality) and more.

Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Kevin Tang <redacted>

v2:
  - Use drm_xxx to replace all DRM_XXX.
  - Use kzalloc to replace devm_kzalloc for sprd_dpu structure init.

v3:
  - Remove dpu_layer stuff layer and commit layers by aotmic_update

v4:
  - Use drmm_helpers to allocate crtc and planes.
  - Move rotation enum definitions to crtc layer reg bitfields.
  - Move allocate crtc and planes to bind funtion.

There's a number of checkpatch warnings, make sure to fix them

Is that the IOMMU page fault interrupt? I would expect it to be in the iommu driver.

+		for (i = 0; i < 8; i++) {
+			reg_val = layer_reg_rd(ctx, REG_LAY_CTRL, i);
+			if (reg_val & 0x1)
+				drm_info(dpu->drm, "layer%d: 0x%08x 0x%08x 0x%08x ctrl: 0x%08x\n", i,
+					layer_reg_rd(ctx, REG_LAY_BASE_ADDR0, i),
+					layer_reg_rd(ctx, REG_LAY_BASE_ADDR1, i),
+					layer_reg_rd(ctx, REG_LAY_BASE_ADDR2, i),
+					layer_reg_rd(ctx, REG_LAY_CTRL, i));
+		}
+	}
+
+	return val;
+}
+
+static int dpu_wait_stop_done(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+	int rc;
+
+	if (ctx->stopped)
+		return 0;
+
+	rc = wait_event_interruptible_timeout(ctx->wait_queue, ctx->evt_stop,
+					       msecs_to_jiffies(500));
+	ctx->evt_stop = false;
+
+	ctx->stopped = true;
+
+	if (!rc) {
+		drm_err(dpu->drm, "dpu wait for stop done time out!\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int dpu_wait_update_done(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+	int rc;
+
+	ctx->evt_update = false;
+
+	rc = wait_event_interruptible_timeout(ctx->wait_queue, ctx->evt_update,
+					       msecs_to_jiffies(500));
+
+	if (!rc) {
+		drm_err(dpu->drm, "dpu wait for reg update done time out!\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static u32 drm_format_to_dpu(struct drm_framebuffer *fb)
+{
+	u32 format = 0;
+
+	switch (fb->format->format) {
+	case DRM_FORMAT_BGRA8888:
+		/* BGRA8888 -> ARGB8888 */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B3B2B1B0;
+		format |= BIT_DPU_LAY_FORMAT_ARGB8888;
+		break;
+	case DRM_FORMAT_RGBX8888:
+	case DRM_FORMAT_RGBA8888:
+		/* RGBA8888 -> ABGR8888 */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B3B2B1B0;
+		/* fallthrough */
+	case DRM_FORMAT_ABGR8888:
+		/* RB switch */
+		format |= BIT_DPU_LAY_RB_OR_UV_SWITCH;
+		/* fallthrough */
+	case DRM_FORMAT_ARGB8888:
+		format |= BIT_DPU_LAY_FORMAT_ARGB8888;
+		break;
+	case DRM_FORMAT_XBGR8888:
+		/* RB switch */
+		format |= BIT_DPU_LAY_RB_OR_UV_SWITCH;
+		/* fallthrough */
+	case DRM_FORMAT_XRGB8888:
+		format |= BIT_DPU_LAY_FORMAT_ARGB8888;
+		break;
+	case DRM_FORMAT_BGR565:
+		/* RB switch */
+		format |= BIT_DPU_LAY_RB_OR_UV_SWITCH;
+		/* fallthrough */
+	case DRM_FORMAT_RGB565:
+		format |= BIT_DPU_LAY_FORMAT_RGB565;
+		break;
+	case DRM_FORMAT_NV12:
+		/* 2-Lane: Yuv420 */
+		format |= BIT_DPU_LAY_FORMAT_YUV420_2PLANE;
+		/* Y endian */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B0B1B2B3;
+		/* UV endian */
+		format |= BIT_DPU_LAY_NO_SWITCH;
+		break;
+	case DRM_FORMAT_NV21:
+		/* 2-Lane: Yuv420 */
+		format |= BIT_DPU_LAY_FORMAT_YUV420_2PLANE;
+		/* Y endian */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B0B1B2B3;
+		/* UV endian */
+		format |= BIT_DPU_LAY_RB_OR_UV_SWITCH;
+		break;
+	case DRM_FORMAT_NV16:
+		/* 2-Lane: Yuv422 */
+		format |= BIT_DPU_LAY_FORMAT_YUV422_2PLANE;
+		/* Y endian */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B3B2B1B0;
+		/* UV endian */
+		format |= BIT_DPU_LAY_RB_OR_UV_SWITCH;
+		break;
+	case DRM_FORMAT_NV61:
+		/* 2-Lane: Yuv422 */
+		format |= BIT_DPU_LAY_FORMAT_YUV422_2PLANE;
+		/* Y endian */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B0B1B2B3;
+		/* UV endian */
+		format |= BIT_DPU_LAY_NO_SWITCH;
+		break;
+	case DRM_FORMAT_YUV420:
+		format |= BIT_DPU_LAY_FORMAT_YUV420_3PLANE;
+		/* Y endian */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B0B1B2B3;
+		/* UV endian */
+		format |= BIT_DPU_LAY_NO_SWITCH;
+		break;
+	case DRM_FORMAT_YVU420:
+		format |= BIT_DPU_LAY_FORMAT_YUV420_3PLANE;
+		/* Y endian */
+		format |= BIT_DPU_LAY_DATA_ENDIAN_B0B1B2B3;
+		/* UV endian */
+		format |= BIT_DPU_LAY_RB_OR_UV_SWITCH;
+		break;
+	default:
+		break;
+	}
+
+	return format;
+}
+
+static u32 drm_rotation_to_dpu(struct drm_plane_state *state)
+{
+	u32 rotation = 0;
+
+	switch (state->rotation) {
+	default:
+	case DRM_MODE_ROTATE_0:
+		rotation = BIT_DPU_LAY_ROTATION_0;
+		break;
+	case DRM_MODE_ROTATE_90:
+		rotation = BIT_DPU_LAY_ROTATION_90;
+		break;
+	case DRM_MODE_ROTATE_180:
+		rotation = BIT_DPU_LAY_ROTATION_180;
+		break;
+	case DRM_MODE_ROTATE_270:
+		rotation = BIT_DPU_LAY_ROTATION_270;
+		break;
+	case DRM_MODE_REFLECT_Y:
+		rotation = BIT_DPU_LAY_ROTATION_180_M;
+		break;
+	case (DRM_MODE_REFLECT_Y | DRM_MODE_ROTATE_90):
+		rotation = BIT_DPU_LAY_ROTATION_90_M;
+		break;
+	case DRM_MODE_REFLECT_X:
+		rotation = BIT_DPU_LAY_ROTATION_0_M;
+		break;
+	case (DRM_MODE_REFLECT_X | DRM_MODE_ROTATE_90):
+		rotation = BIT_DPU_LAY_ROTATION_270_M;
+		break;
+	}
+
+	return rotation;
+}
+
+static u32 drm_blend_to_dpu(struct drm_plane_state *state)
+{
+	u32 blend = 0;
+
+	switch (state->pixel_blend_mode) {
+	case DRM_MODE_BLEND_COVERAGE:
+		/* alpha mode select - combo alpha */
+		blend |= BIT_DPU_LAY_COMBO_ALPHA;
+		/* Normal mode */
+		blend |= BIT_DPU_LAY_MODE_BLEND_NORMAL;
+		break;
+	case DRM_MODE_BLEND_PREMULTI:
+		/* alpha mode select - combo alpha */
+		blend |= BIT_DPU_LAY_COMBO_ALPHA;
+		/* Pre-mult mode */
+		blend |= BIT_DPU_LAY_MODE_BLEND_PREMULT;
+		break;
+	case DRM_MODE_BLEND_PIXEL_NONE:
+	default:
+		/* don't do blending, maybe RGBX */
+		/* alpha mode select - layer alpha */
+		blend |= BIT_DPU_LAY_LAYER_ALPHA;
+		break;
+	}
+
+	return blend;
+}
+
+static void sprd_dpu_layer(struct sprd_dpu *dpu, struct sprd_plane *plane,
+			struct drm_plane_state *state)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+	struct drm_gem_cma_object *cma_obj;
+	const struct drm_format_info *info;
+	struct drm_framebuffer *fb = state->fb;
+	u32 addr, size, offset, pitch, blend, format, rotation;
+	u32 src_x = state->src_x >> 16;
+	u32 src_y = state->src_y >> 16;
+	u32 src_w = state->src_w >> 16;
+	u32 src_h = state->src_h >> 16;
+	u32 dst_x = state->crtc_x;
+	u32 dst_y = state->crtc_y;
+	u32 alpha = state->alpha;
+	int i;
+
+	offset = (dst_x & 0xffff) | (dst_y << 16);
+	size = (src_w & 0xffff) | (src_h << 16);
+
+	for (i = 0; i < fb->format->num_planes; i++) {
+		cma_obj = drm_fb_cma_get_gem_obj(fb, i);
+		addr = cma_obj->paddr + fb->offsets[i];
+
+		if (i == 0)
+			layer_reg_wr(ctx, REG_LAY_BASE_ADDR0, addr, plane->index);
+		else if (i == 1)
+			layer_reg_wr(ctx, REG_LAY_BASE_ADDR1, addr, plane->index);
+		else
+			layer_reg_wr(ctx, REG_LAY_BASE_ADDR2, addr, plane->index);
+	}
+
+	info = drm_format_info(fb->format->format);
+	if (fb->format->num_planes == 3) {
+		/* UV pitch is 1/2 of Y pitch */
+		pitch = (fb->pitches[0] / info->cpp[0]) |
+				(fb->pitches[0] / info->cpp[0] << 15);
+	} else {
+		pitch = fb->pitches[0] / info->cpp[0];
+	}
+
+	layer_reg_wr(ctx, REG_LAY_POS, offset, plane->index);
+	layer_reg_wr(ctx, REG_LAY_SIZE, size, plane->index);
+	layer_reg_wr(ctx, REG_LAY_CROP_START,
+			src_y << 16 | src_x, plane->index);
+	layer_reg_wr(ctx, REG_LAY_ALPHA, alpha, plane->index);
+	layer_reg_wr(ctx, REG_LAY_PITCH, pitch, plane->index);
+
+	format = drm_format_to_dpu(fb);
+	blend = drm_blend_to_dpu(state);
+	rotation = drm_rotation_to_dpu(state);
+
+	layer_reg_wr(ctx, REG_LAY_CTRL, BIT_DPU_LAY_EN |
+				format |
+				blend |
+				rotation,
+				plane->index);
+}
+
+static void sprd_dpu_flip(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+	u32 reg_val;
+
+	/*
+	 * Make sure the dpu is in stop status. DPU has no shadow
+	 * registers in EDPI mode. So the config registers can only be
+	 * updated in the rising edge of DPU_RUN bit.
+	 */
+	if (ctx->if_type == SPRD_DPU_IF_EDPI)
+		dpu_wait_stop_done(dpu);
+
+	/* update trigger and wait */
+	if (ctx->if_type == SPRD_DPU_IF_DPI) {
+		if (!ctx->stopped) {
+			dpu_reg_set(ctx, REG_DPU_CTRL, BIT_DPU_REG_UPDATE);
+			dpu_wait_update_done(dpu);
+		}
+
+		dpu_reg_set(ctx, REG_DPU_INT_EN, BIT_DPU_INT_ERR);
+	} else if (ctx->if_type == SPRD_DPU_IF_EDPI) {
+		dpu_reg_set(ctx, REG_DPU_CTRL, BIT_DPU_RUN);
+
+		ctx->stopped = false;
+	}
+
+	/*
+	 * If the following interrupt was disabled in isr,
+	 * re-enable it.
+	 */
+	reg_val = BIT_DPU_INT_MMU_VAOR_RD |
+		  BIT_DPU_INT_MMU_VAOR_WR |
+		  BIT_DPU_INT_MMU_INV_RD |
+		  BIT_DPU_INT_MMU_INV_WR;
+	dpu_reg_set(ctx, REG_DPU_INT_EN, reg_val);
+}
+
+static void sprd_dpu_init(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+	u32 size;
+
+	writel(0x00, ctx->base + REG_BG_COLOR);
+
+	size = (ctx->vm.vactive << 16) | ctx->vm.hactive;
+	writel(size, ctx->base + REG_PANEL_SIZE);
+	writel(size, ctx->base + REG_BLEND_SIZE);
+
+	writel(0x00, ctx->base + REG_MMU_EN);
+	writel(0x00, ctx->base + REG_MMU_PPN1);
+	writel(0xffff, ctx->base + REG_MMU_RANGE1);
+	writel(0x00, ctx->base + REG_MMU_PPN2);
+	writel(0xffff, ctx->base + REG_MMU_RANGE2);
+	writel(0x1ffff, ctx->base + REG_MMU_VPN_RANGE);
+}
+
+static void sprd_dpu_fini(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+
+	writel(0x00, ctx->base + REG_DPU_INT_EN);
+	writel(0xff, ctx->base + REG_DPU_INT_CLR);
+}
+
+static void sprd_dpi_init(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+	u32 int_mask = 0;
+	u32 reg_val;
+
+	if (ctx->if_type == SPRD_DPU_IF_DPI) {
+		/* use dpi as interface */
+		dpu_reg_clr(ctx, REG_DPU_CFG0, BIT_DPU_IF_EDPI);
+		/* disable Halt function for SPRD DSI */
+		dpu_reg_clr(ctx, REG_DPI_CTRL, BIT_DPU_DPI_HALT_EN);
+		/* select te from external pad */
+		dpu_reg_set(ctx, REG_DPI_CTRL, BIT_DPU_EDPI_FROM_EXTERNAL_PAD);
+
+		/* set dpi timing */
+		reg_val = ctx->vm.hsync_len << 0 |
+			  ctx->vm.hback_porch << 8 |
+			  ctx->vm.hfront_porch << 20;
+		writel(reg_val, ctx->base + REG_DPI_H_TIMING);
+
+		reg_val = ctx->vm.vsync_len << 0 |
+			  ctx->vm.vback_porch << 8 |
+			  ctx->vm.vfront_porch << 20;
+		writel(reg_val, ctx->base + REG_DPI_V_TIMING);
+
+		if (ctx->vm.vsync_len + ctx->vm.vback_porch < 32)
+			drm_warn(dpu->drm, "Warning: (vsync + vbp) < 32, "
+				"underflow risk!\n");

I don't think a warning is appropriate here. Maybe we should just
outright reject any mode that uses it?

+		/* enable dpu update done INT */
+		int_mask |= BIT_DPU_INT_UPDATE_DONE;
+		/* enable dpu done INT */
+		int_mask |= BIT_DPU_INT_DONE;
+		/* enable dpu dpi vsync */
+		int_mask |= BIT_DPU_INT_VSYNC;
+		/* enable dpu TE INT */
+		int_mask |= BIT_DPU_INT_TE;
+		/* enable underflow err INT */
+		int_mask |= BIT_DPU_INT_ERR;
+	} else if (ctx->if_type == SPRD_DPU_IF_EDPI) {
+		/* use edpi as interface */
+		dpu_reg_set(ctx, REG_DPU_CFG0, BIT_DPU_IF_EDPI);
+		/* use external te */
+		dpu_reg_set(ctx, REG_DPI_CTRL, BIT_DPU_EDPI_FROM_EXTERNAL_PAD);
+		/* enable te */
+		dpu_reg_set(ctx, REG_DPI_CTRL, BIT_DPU_EDPI_TE_EN);
+
+		/* enable stop done INT */
+		int_mask |= BIT_DPU_INT_DONE;
+		/* enable TE INT */
+		int_mask |= BIT_DPU_INT_TE;
+	}
+
+	/* enable iommu va out of range read error INT */
+	int_mask |= BIT_DPU_INT_MMU_VAOR_RD;
+	/* enable iommu va out of range write error INT */
+	int_mask |= BIT_DPU_INT_MMU_VAOR_WR;
+	/* enable iommu invalid read error INT */
+	int_mask |= BIT_DPU_INT_MMU_INV_RD;
+	/* enable iommu invalid write error INT */
+	int_mask |= BIT_DPU_INT_MMU_INV_WR;
+
+	writel(int_mask, ctx->base + REG_DPU_INT_EN);
+}
+
+void sprd_dpu_run(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+
+	dpu_reg_set(ctx, REG_DPU_CTRL, BIT_DPU_RUN);
+
+	ctx->stopped = false;
+}
+
+void sprd_dpu_stop(struct sprd_dpu *dpu)
+{
+	struct dpu_context *ctx = &dpu->ctx;
+
+	if (ctx->if_type == SPRD_DPU_IF_DPI)
+		dpu_reg_set(ctx, REG_DPU_CTRL, BIT_DPU_STOP);
+
+	dpu_wait_stop_done(dpu);
+}
+
+static int sprd_plane_atomic_check(struct drm_plane *plane,
+				  struct drm_plane_state *state)
+{
+	struct drm_framebuffer *fb = state->fb;
+	struct drm_crtc_state *crtc_state;
+	u32 fmt;
+
+	if (!fb || !state->crtc)
+		return 0;
+
+	fmt = drm_format_to_dpu(fb);
+	if (!fmt)
+		return -EINVAL;
+
+	crtc_state = drm_atomic_get_crtc_state(state->state, state->crtc);
+	if (IS_ERR(crtc_state))
+		return PTR_ERR(crtc_state);
+
+	return drm_atomic_helper_check_plane_state(state, crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  true, true);
+}
+
+static void sprd_plane_atomic_update(struct drm_plane *drm_plane,
+				    struct drm_plane_state *old_state)
+{
+	struct drm_plane_state *state = drm_plane->state;
+	struct sprd_plane *plane = to_sprd_plane(drm_plane);
+	struct sprd_dpu *dpu = to_sprd_crtc(state->crtc);
+
+	/* start configure dpu layers */
+	sprd_dpu_layer(dpu, plane, state);
+}
+
+static void sprd_plane_atomic_disable(struct drm_plane *drm_plane,
+				     struct drm_plane_state *old_state)
+{
+	struct sprd_plane *plane = to_sprd_plane(drm_plane);
+	struct sprd_dpu *dpu = to_sprd_crtc(old_state->crtc);
+
+	layer_reg_wr(&dpu->ctx, REG_LAY_CTRL, 0x00, plane->index);
+}
+
+static void sprd_plane_create_properties(struct sprd_plane *plane, int index)
+{
+	unsigned int supported_modes = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
+				       BIT(DRM_MODE_BLEND_PREMULTI) |
+				       BIT(DRM_MODE_BLEND_COVERAGE);
+
+	/* create rotation property */
+	drm_plane_create_rotation_property(&plane->base,
+					   DRM_MODE_ROTATE_0,
+					   DRM_MODE_ROTATE_MASK |
+					   DRM_MODE_REFLECT_MASK);
+
+	/* create alpha property */
+	drm_plane_create_alpha_property(&plane->base);
+
+	/* create blend mode property */
+	drm_plane_create_blend_mode_property(&plane->base, supported_modes);
+
+	/* create zpos property */
+	drm_plane_create_zpos_immutable_property(&plane->base, index);
+}
+
+static const struct drm_plane_helper_funcs sprd_plane_helper_funcs = {
+	.atomic_check = sprd_plane_atomic_check,
+	.atomic_update = sprd_plane_atomic_update,
+	.atomic_disable = sprd_plane_atomic_disable,
+};
+
+static const struct drm_plane_funcs sprd_plane_funcs = {
+	.update_plane = drm_atomic_helper_update_plane,
+	.disable_plane	= drm_atomic_helper_disable_plane,
+	.destroy = drm_plane_cleanup,
+	.reset = drm_atomic_helper_plane_reset,
+	.atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
+};
+
+static struct sprd_plane *sprd_plane_init(struct drm_device *drm)
+{
+	struct sprd_plane *plane, *primary;
+	int i;
+
+	for (i = 0; i < 6; i++) {
+		plane = drmm_universal_plane_alloc(drm, struct sprd_plane, base,
+					       1, &sprd_plane_funcs,
+					       primary_fmts, ARRAY_SIZE(primary_fmts),
+					       NULL, DRM_PLANE_TYPE_PRIMARY, NULL);
+		if (IS_ERR(plane)) {
+			drm_err(drm, "fail to init primary plane\n");
+			return plane;
+		}
+
+		drm_plane_helper_add(&plane->base, &sprd_plane_helper_funcs);
+
+		sprd_plane_create_properties(plane, i);
+
+		plane->index = i;
+		if (i == 0)
+			primary = plane;
+	}
+
+	return primary;
+}
+
+static enum drm_mode_status sprd_crtc_mode_valid(struct drm_crtc *crtc,
+					const struct drm_display_mode *mode)
+{
+	struct sprd_dpu *dpu = to_sprd_crtc(crtc);
+
+	drm_dbg(dpu->drm, "%s() mode: "DRM_MODE_FMT"\n", __func__, DRM_MODE_ARG(mode));
+
+	if (mode->type & DRM_MODE_TYPE_PREFERRED) {
+		drm_display_mode_to_videomode(mode, &dpu->ctx.vm);

You don't seem to use that anywhere else? And that's a bit fragile,
nothing really guarantees that it's the mode you're going to use, and
even then it can be adjusted.

+
+		if ((mode->hdisplay == mode->htotal) ||
+		    (mode->vdisplay == mode->vtotal))
+			dpu->ctx.if_type = SPRD_DPU_IF_EDPI;
+		else
+			dpu->ctx.if_type = SPRD_DPU_IF_DPI;

From an API PoV, you would want that to be in atomic_check. However, I'm
not even sure what it's doing in the first place?

+	}
+
+	return MODE_OK;
+}
+
+static void sprd_crtc_atomic_enable(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	struct sprd_dpu *dpu = to_sprd_crtc(crtc);
+
+	sprd_dpu_init(dpu);
+
+	sprd_dpi_init(dpu);
+
+	enable_irq(dpu->ctx.irq);

Shouldn't this be in enable_vblank? And I would assume that you would
have the interrupts enabled all the time, but disabled in your device?

+	drm_crtc_vblank_on(&dpu->base);
+}
+
+static void sprd_crtc_atomic_disable(struct drm_crtc *crtc,
+				    struct drm_atomic_state *state)
+{
+	struct sprd_dpu *dpu = to_sprd_crtc(crtc);
+	struct drm_device *drm = dpu->base.dev;
+
+	drm_crtc_vblank_off(&dpu->base);
+
+	disable_irq(dpu->ctx.irq);
+
+	sprd_dpu_fini(dpu);
+
+	spin_lock_irq(&drm->event_lock);
+	if (crtc->state->event) {
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&drm->event_lock);
+}
+
+static int sprd_crtc_atomic_check(struct drm_crtc *crtc,
+				 struct drm_atomic_state *state)
+{
+	drm_dbg(crtc->dev, "%s()\n", __func__);
+
+	return 0;
+}
+
+static void sprd_crtc_atomic_flush(struct drm_crtc *crtc,
+				  struct drm_atomic_state *state)
+
+{
+	struct sprd_dpu *dpu = to_sprd_crtc(crtc);
+	struct drm_device *drm = dpu->base.dev;
+
+	sprd_dpu_flip(dpu);
+
+	spin_lock_irq(&drm->event_lock);
+	if (crtc->state->event) {
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&drm->event_lock);
+}
+
+static int sprd_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+	struct sprd_dpu *dpu = to_sprd_crtc(crtc);
+
+	dpu_reg_set(&dpu->ctx, REG_DPU_INT_EN, BIT_DPU_INT_VSYNC);
+
+	return 0;
+}
+
+static void sprd_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+	struct sprd_dpu *dpu = to_sprd_crtc(crtc);
+
+	dpu_reg_clr(&dpu->ctx, REG_DPU_INT_EN, BIT_DPU_INT_VSYNC);
+}
+
+static const struct drm_crtc_helper_funcs sprd_crtc_helper_funcs = {
+	.mode_valid	= sprd_crtc_mode_valid,
+	.atomic_check	= sprd_crtc_atomic_check,
+	.atomic_flush	= sprd_crtc_atomic_flush,
+	.atomic_enable	= sprd_crtc_atomic_enable,
+	.atomic_disable	= sprd_crtc_atomic_disable,
+};
+
+static const struct drm_crtc_funcs sprd_crtc_funcs = {
+	.destroy	= drm_crtc_cleanup,
+	.set_config	= drm_atomic_helper_set_config,
+	.page_flip	= drm_atomic_helper_page_flip,
+	.reset		= drm_atomic_helper_crtc_reset,
+	.atomic_duplicate_state	= drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_crtc_destroy_state,
+	.enable_vblank	= sprd_crtc_enable_vblank,
+	.disable_vblank	= sprd_crtc_disable_vblank,
+};
+
+static struct sprd_dpu *sprd_crtc_init(struct drm_device *drm,
+			 struct drm_plane *primary)
+{
+	struct device_node *port;
+	struct sprd_dpu *dpu;
+
+	/*
+	 * set crtc port so that drm_of_find_possible_crtcs call works
+	 */
+	port = of_parse_phandle(drm->dev->of_node, "ports", 0);
+	if (!port) {
+		drm_err(drm, "find 'ports' phandle of %s failed\n",
+			  drm->dev->of_node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
+	of_node_put(port);

The YAML binding should already make sure that your binding is sane, and
if you still get a DT that doesn't follow it, you have a whole lot of
other issues than whether ports is there :)

+	dpu = drmm_crtc_alloc_with_planes(drm, struct sprd_dpu, base,
+					primary, NULL,
+					&sprd_crtc_funcs, NULL);
+	if (IS_ERR(dpu)) {
+		drm_err(drm, "failed to init crtc.\n");
+		return dpu;
+	}
+
+	dpu->base.port = port;

But you're still referencing it here, while you called of_node_put on it
already? You should only call it once you're done with it.

I'm not really sure why you would need drm_of_find_possible_crtcs to
work then if you don't follow the OF-Graph bindings.

Maxime