drm/stm: ltdc: reset ltdc on crtc enable

To avoid any blocking point between uboot and the kernel, ltdc must be reset. To have a continuous display, the reset is conditional on the boolean "default-on". The reset must be done when activating the crtc. Change-Id: I1f8c31087ea28fab4ff56400f1aa863541ed08c3 Signed-off-by: Yannick Fertre <[email protected]> Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/linux-stm32/+/416185
STMicroelectronics · Nov 4, 2024 · 3682d60 · 3682d60
1 parent 49ba6ad
commit 3682d60
Show file tree

Hide file tree

Showing 2 changed files with 16 additions and 6 deletions.
diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
@@ -810,8 +810,18 @@ static void ltdc_crtc_atomic_enable(struct drm_crtc *crtc,
 
 	DRM_DEBUG_DRIVER("\n");
 
-	if (pm_runtime_active(ddev->dev))
+	if (pm_runtime_active(ddev->dev)) {
+		if (!IS_ERR(ldev->rstc)) {
+			reset_control_assert(ldev->rstc);
+			usleep_range(10, 20);
+			reset_control_deassert(ldev->rstc);
+		}
+
+		/* Wait a while to clear the current display */
+		mdelay(30);
+
 		pm_runtime_put_sync_suspend(ddev->dev);
+	}
 
 	/* get encoder from crtc */
 	drm_for_each_encoder(en_iter, ddev)
@@ -2413,7 +2423,6 @@ int ltdc_load(struct drm_device *ddev)
 	struct drm_bridge *bridge;
 	struct drm_panel *panel;
 	struct drm_crtc *crtc;
-	struct reset_control *rstc;
 	struct resource *res;
 	int irq, i, nb_endpoints;
 	int ret = -ENODEV;
@@ -2472,7 +2481,7 @@ int ltdc_load(struct drm_device *ddev)
 		}
 	}
 
-	rstc = devm_reset_control_get_exclusive(dev, NULL);
+	ldev->rstc = devm_reset_control_get_exclusive(dev, NULL);
 
 	mutex_init(&ldev->err_lock);
 
@@ -2483,10 +2492,10 @@ int ltdc_load(struct drm_device *ddev)
 	 * remain activated and reset shouldn't be done
 	 */
 	if (!def_value) {
-		if (!IS_ERR(rstc)) {
-			reset_control_assert(rstc);
+		if (!IS_ERR(ldev->rstc)) {
+			reset_control_assert(ldev->rstc);
 			usleep_range(10, 20);
-			reset_control_deassert(rstc);
+			reset_control_deassert(ldev->rstc);
 		}
 	}
 

diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
@@ -71,6 +71,7 @@ struct ltdc_device {
 	u32 crc;
 	u32 max_burst_length;
 	struct reserved_mem *rot_mem;
+	struct reset_control *rstc;
 	struct stm32_firewall firewall[LTDC_MAX_FIREWALL];
 	bool plane_enabled[LTDC_MAX_LAYER];
 };