[PATCH v7 06/15] drm/imx: dc-crtc: Disable at boot

[Liu Ying]

CRTC(s) could still be running after the DRM device is unplugged by
calling drm_dev_unplug(), because the CRTC disablement logic is
protected and bypassed by the drm_dev_enter()/drm_dev_exit() pair.
Hence, Pixel Engine's AXI clock use count(managed by Pixel Engine
driver's runtime PM) and pixel clock use count could be inbalanced
after removing and re-installing the driver module.  To fix this,
add a helper dc_crtc_disable_at_boot() and call it to properly
disable all CRTCs before advertising DRM device to user-space by
calling drm_dev_register().

Fixes: 711a3b878366 ("drm/imx: Add i.MX8qxp Display Controller KMS")
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
--
v7:
- Check CRTC status to ensure that clocks were enabled by a previous boot
  before disabling them in dc_crtc_disable_at_boot().  (Sashiko AI bot)
- Modify debug message in dc_crtc_disable_at_boot().

v6:
- Rebase onto the latest drm-misc-next and resolve conflicts.

v3:
- Collect Frank's R-b tag.
---
 drivers/gpu/drm/imx/dc/dc-crtc.c | 67 ++++++++++++++++++++++++++++++++++------
 drivers/gpu/drm/imx/dc/dc-drv.c  |  5 +++
 drivers/gpu/drm/imx/dc/dc-drv.h  |  3 ++
 3 files changed, 65 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/imx/dc/dc-crtc.c b/drivers/gpu/drm/imx/dc/dc-crtc.c
index 0d64186a9901..c7dbe5f500b4 100644
--- a/drivers/gpu/drm/imx/dc/dc-crtc.c
+++ b/drivers/gpu/drm/imx/dc/dc-crtc.c
@@ -227,6 +227,7 @@ dc_crtc_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_commit *state)
 	struct drm_crtc_state *new_crtc_state =
 				drm_atomic_get_new_crtc_state(state, crtc);
 	struct drm_display_mode *adj = &new_crtc_state->adjusted_mode;
+	struct dc_drm_device *dc_drm = to_dc_drm_device(crtc->dev);
 	struct dc_crtc *dc_crtc = to_dc_crtc(crtc);
 	enum dc_link_id cf_link;
 	int idx, ret;
@@ -287,29 +288,37 @@ dc_crtc_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_commit *state)
 
 	DC_CRTC_CHECK_FRAMEGEN_FIFO(dc_crtc->fg);
 
+	dc_drv_set_crtc_enable(dc_drm, drm_crtc_index(crtc));
+
 	drm_dev_exit(idx);
 
 out:
 	dc_crtc_queue_state_event(new_crtc_state);
 }
 
-static void
-dc_crtc_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_commit *state)
+static inline void __dc_crtc_disable_fg(struct drm_crtc *crtc)
 {
-	struct drm_crtc_state *new_crtc_state =
-				drm_atomic_get_new_crtc_state(state, crtc);
-	struct dc_drm_device *dc_drm = to_dc_drm_device(crtc->dev);
 	struct dc_crtc *dc_crtc = to_dc_crtc(crtc);
-	int idx;
-
-	if (!drm_dev_enter(crtc->dev, &idx))
-		goto out;
 
 	enable_irq(dc_crtc->irq_dec_seqcomplete);
 	dc_fg_disable(dc_crtc->fg);
 	DC_CRTC_WAIT_FOR_COMPLETION_TIMEOUT(dec_seqcomplete_done);
 	disable_irq(dc_crtc->irq_dec_seqcomplete);
+}
 
+static void
+dc_crtc_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_commit *state)
+{
+	struct drm_crtc_state *new_crtc_state =
+				drm_atomic_get_new_crtc_state(state, crtc);
+	struct dc_drm_device *dc_drm = to_dc_drm_device(crtc->dev);
+	struct dc_crtc *dc_crtc = to_dc_crtc(crtc);
+	int idx;
+
+	if (!drm_dev_enter(crtc->dev, &idx))
+		goto out;
+
+	__dc_crtc_disable_fg(crtc);
 	dc_fg_disable_clock(dc_crtc->fg);
 
 	/* request pixel engine power-off as plane is off too */
@@ -318,8 +327,9 @@ dc_crtc_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_commit *state)
 	/* request display engine power-off when CRTC is disabled */
 	pm_runtime_put(dc_crtc->de->dev);
 
-	drm_dev_exit(idx);
+	dc_drv_set_crtc_disable(dc_drm, drm_crtc_index(crtc));
 
+	drm_dev_exit(idx);
 out:
 	drm_crtc_vblank_off(crtc);
 
@@ -331,6 +341,43 @@ dc_crtc_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_commit *state)
 	spin_unlock_irq(&crtc->dev->event_lock);
 }
 
+void dc_crtc_disable_at_boot(struct drm_crtc *crtc)
+{
+	struct dc_drm_device *dc_drm = to_dc_drm_device(crtc->dev);
+	struct dc_crtc *dc_crtc = to_dc_crtc(crtc);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dc_crtc->de->dev);
+	if (ret < 0) {
+		dc_crtc_err(crtc, "failed to get DC display engine RPM: %d\n",
+			    ret);
+		return;
+	}
+
+	if (!dc_fg_wait_for_frame_index_moving(dc_crtc->fg)) {
+		dc_crtc_dbg(crtc, "FrameGen frame index isn't moving\n");
+		goto out;
+	}
+
+	dc_crtc_dbg(crtc, "disabling FrameGen at boot\n");
+	__dc_crtc_disable_fg(crtc);
+
+	if (!dc_drv_crtc_was_enabled(dc_drm, drm_crtc_index(crtc)))
+		goto out;
+
+	dc_crtc_dbg(crtc, "disabling clocks at boot\n");
+
+	dc_fg_disable_clock(dc_crtc->fg);
+
+	if (!dc_drm->pe_clk_axi_disabled) {
+		clk_disable_unprepare(dc_drm->pe->clk_axi);
+		dc_drm->pe_clk_axi_disabled = true;
+	}
+
+out:
+	pm_runtime_put(dc_crtc->de->dev);
+}
+
 static bool dc_crtc_get_scanout_position(struct drm_crtc *crtc,
 					 bool in_vblank_irq,
 					 int *vpos, int *hpos,
diff --git a/drivers/gpu/drm/imx/dc/dc-drv.c b/drivers/gpu/drm/imx/dc/dc-drv.c
index ac1321adf1c8..09387d62cc0b 100644
--- a/drivers/gpu/drm/imx/dc/dc-drv.c
+++ b/drivers/gpu/drm/imx/dc/dc-drv.c
@@ -17,6 +17,7 @@
 
 #include <drm/clients/drm_client_setup.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_fbdev_dma.h>
 #include <drm/drm_fourcc.h>
@@ -108,6 +109,7 @@ static int dc_drm_bind(struct device *dev)
 	struct dc_priv *priv = dev_get_drvdata(dev);
 	struct dc_drm_device *dc_drm;
 	struct drm_device *drm;
+	struct drm_crtc *crtc;
 	int ret;
 
 	dc_drm = devm_drm_dev_alloc(dev, &dc_drm_driver, struct dc_drm_device,
@@ -130,6 +132,9 @@ static int dc_drm_bind(struct device *dev)
 	if (ret)
 		return ret;
 
+	drm_for_each_crtc(crtc, drm)
+		dc_crtc_disable_at_boot(crtc);
+
 	ret = drm_dev_register(drm, 0);
 	if (ret) {
 		dev_err(dev, "failed to register drm device: %d\n", ret);
diff --git a/drivers/gpu/drm/imx/dc/dc-drv.h b/drivers/gpu/drm/imx/dc/dc-drv.h
index dd1302382ab0..1ec9304329eb 100644
--- a/drivers/gpu/drm/imx/dc/dc-drv.h
+++ b/drivers/gpu/drm/imx/dc/dc-drv.h
@@ -50,6 +50,8 @@ struct dc_drm_device {
 	struct dc_pe *pe;
 	/** @tc: tcon list */
 	struct dc_tc *tc[DC_DISPLAYS];
+	/** @pe_clk_axi_disabled: disablement flag at boot */
+	bool pe_clk_axi_disabled;
 };
 
 struct dc_subdev_info {
@@ -96,6 +98,7 @@ static inline int dc_subdev_get_id(const struct dc_subdev_info *info,
 	return -EINVAL;
 }
 
+void dc_crtc_disable_at_boot(struct drm_crtc *crtc);
 void dc_de_post_bind(struct dc_drm_device *dc_drm);
 void dc_pe_post_bind(struct dc_drm_device *dc_drm);
 

-- 
2.43.0