drm: hdlcd: Revamp runtime power management

Because the HDLCD driver acts as a component master it can end
up enabling the runtime PM functionality before the encoders
are initialised. This can cause crashes if the component slave
never probes (missing module) or if the PM operations kick in
before the probe finishes.

Move the enabling of the runtime PM after the component master
has finished collecting the slave components and use the DRM
atomic helpers to suspend and resume the device.

Tested-by: Robin Murphy <Robin.Murphy@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

1 files changed, 27 insertions, 21 deletions

diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c b/drivers/gpu/drm/arm/hdlcd_drv.c
index b987c63ba8d6..21b1427fc918 100644
--- a/drivers/gpu/drm/arm/hdlcd_drv.c
+++ b/drivers/gpu/drm/arm/hdlcd_drv.c
@@ -84,11 +84,7 @@ static int hdlcd_load(struct drm_device *drm, unsigned long flags)
 		goto setup_fail;
 	}
 
-	pm_runtime_enable(drm->dev);
-
-	pm_runtime_get_sync(drm->dev);
 	ret = drm_irq_install(drm, platform_get_irq(pdev, 0));
-	pm_runtime_put_sync(drm->dev);
 	if (ret < 0) {
 		DRM_ERROR("failed to install IRQ handler\n");
 		goto irq_fail;
@@ -357,6 +353,8 @@ static int hdlcd_drm_bind(struct device *dev)
 		return -ENOMEM;
 
 	drm->dev_private = hdlcd;
+	dev_set_drvdata(dev, drm);
+
 	hdlcd_setup_mode_config(drm);
 	ret = hdlcd_load(drm, 0);
 	if (ret)
@@ -366,14 +364,18 @@ static int hdlcd_drm_bind(struct device *dev)
 	if (ret)
 		goto err_unload;
 
-	dev_set_drvdata(dev, drm);
-
 	ret = component_bind_all(dev, drm);
 	if (ret) {
 		DRM_ERROR("Failed to bind all components\n");
 		goto err_unregister;
 	}
 
+	ret = pm_runtime_set_active(dev);
+	if (ret)
+		goto err_pm_active;
+
+	pm_runtime_enable(dev);
+
 	ret = drm_vblank_init(drm, drm->mode_config.num_crtc);
 	if (ret < 0) {
 		DRM_ERROR("failed to initialise vblank\n");
@@ -399,16 +401,16 @@ err_fbdev:
 	drm_mode_config_cleanup(drm);
 	drm_vblank_cleanup(drm);
 err_vblank:
+	pm_runtime_disable(drm->dev);
+err_pm_active:
 	component_unbind_all(dev, drm);
 err_unregister:
 	drm_dev_unregister(drm);
 err_unload:
-	pm_runtime_get_sync(drm->dev);
 	drm_irq_uninstall(drm);
-	pm_runtime_put_sync(drm->dev);
-	pm_runtime_disable(drm->dev);
 	of_reserved_mem_device_release(drm->dev);
 err_free:
+	dev_set_drvdata(dev, NULL);
 	drm_dev_unref(drm);
 
 	return ret;
@@ -495,30 +497,34 @@ MODULE_DEVICE_TABLE(of, hdlcd_of_match);
 static int __maybe_unused hdlcd_pm_suspend(struct device *dev)
 {
 	struct drm_device *drm = dev_get_drvdata(dev);
-	struct drm_crtc *crtc;
+	struct hdlcd_drm_private *hdlcd = drm ? drm->dev_private : NULL;
 
-	if (pm_runtime_suspended(dev))
+	if (!hdlcd)
 		return 0;
 
-	drm_modeset_lock_all(drm);
-	list_for_each_entry(crtc, &drm->mode_config.crtc_list, head)
-		hdlcd_crtc_suspend(crtc);
-	drm_modeset_unlock_all(drm);
+	drm_kms_helper_poll_disable(drm);
+
+	hdlcd->state = drm_atomic_helper_suspend(drm);
+	if (IS_ERR(hdlcd->state)) {
+		drm_kms_helper_poll_enable(drm);
+		return PTR_ERR(hdlcd->state);
+	}
+
 	return 0;
 }
 
 static int __maybe_unused hdlcd_pm_resume(struct device *dev)
 {
 	struct drm_device *drm = dev_get_drvdata(dev);
-	struct drm_crtc *crtc;
+	struct hdlcd_drm_private *hdlcd = drm ? drm->dev_private : NULL;
 
-	if (!pm_runtime_suspended(dev))
+	if (!hdlcd)
 		return 0;
 
-	drm_modeset_lock_all(drm);
-	list_for_each_entry(crtc, &drm->mode_config.crtc_list, head)
-		hdlcd_crtc_resume(crtc);
-	drm_modeset_unlock_all(drm);
+	drm_atomic_helper_resume(drm, hdlcd->state);
+	drm_kms_helper_poll_enable(drm);
+	pm_runtime_set_active(dev);
+
 	return 0;
 }