[PATCH 04/11] drm/msm: let the kms drivers clean up a failed kms_init()

[Dmitry Baryshkov]

A failed priv->kms_init() or ->hw_init() is cleaned up by the ->destroy()
callback, which makes ->destroy() responsible for tearing down a KMS in
any state between "not initialised at all" and "fully initialised". The
kernel convention is the opposite: a function which fails undoes its own
steps, and the teardown only ever sees a fully set up object.

Let the kms drivers switch to that convention one at a time: skip
->destroy() after a failed kms_init() of a driver which sets
init_unwinds, and let the drivers fold their hardware setup into
kms_init() and drop ->hw_init(). Set up the mode config before calling
kms_init(), so that it is already in place for the hardware setup.

The flag and the optional ->hw_init() go away once all the drivers have
been converted.

Assisted-by: LLM
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/msm_kms.c | 23 ++++++++++++++---------
 drivers/gpu/drm/msm/msm_kms.h |  3 +++
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
index f3e39c3907a9..f65774b04c6f 100644
--- a/drivers/gpu/drm/msm/msm_kms.c
+++ b/drivers/gpu/drm/msm/msm_kms.c
@@ -285,12 +285,6 @@ int msm_drm_kms_init(struct device *dev, const struct drm_driver *drv)
 		return ret;
 	}
 
-	ret = priv->kms_init(ddev);
-	if (ret) {
-		DRM_DEV_ERROR(dev, "failed to load kms\n");
-		goto err_destroy_kms;
-	}
-
 	/* Enable normalization of plane zpos */
 	ddev->mode_config.normalize_zpos = true;
 
@@ -298,12 +292,22 @@ int msm_drm_kms_init(struct device *dev, const struct drm_driver *drv)
 	ddev->mode_config.helper_private = &mode_config_helper_funcs;
 
 	kms->dev = ddev;
-	ret = kms->funcs->hw_init(kms);
+	ret = priv->kms_init(ddev);
 	if (ret) {
-		DRM_DEV_ERROR(dev, "kms hw init failed: %d\n", ret);
+		DRM_DEV_ERROR(dev, "failed to load kms\n");
+		if (kms->init_unwinds)
+			goto err_destroy_snapshot;
 		goto err_destroy_kms;
 	}
 
+	if (kms->funcs->hw_init) {
+		ret = kms->funcs->hw_init(kms);
+		if (ret) {
+			DRM_DEV_ERROR(dev, "kms hw init failed: %d\n", ret);
+			goto err_destroy_kms;
+		}
+	}
+
 	drm_helper_move_panel_connectors_to_head(ddev);
 
 	drm_for_each_crtc(crtc, ddev) {
@@ -344,9 +348,10 @@ int msm_drm_kms_init(struct device *dev, const struct drm_driver *drv)
 err_destroy_event_threads:
 	msm_drm_kms_destroy_event_threads(kms);
 err_destroy_kms:
-	msm_disp_snapshot_destroy(ddev);
 	if (kms->funcs)
 		kms->funcs->destroy(kms);
+err_destroy_snapshot:
+	msm_disp_snapshot_destroy(ddev);
 
 	return ret;
 }
diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
index ee98393b9855..2f097e23e2e9 100644
--- a/drivers/gpu/drm/msm/msm_kms.h
+++ b/drivers/gpu/drm/msm/msm_kms.h
@@ -149,6 +149,9 @@ struct msm_kms {
 	int irq;
 	bool irq_requested;
 
+	/* set by the kms drivers whose kms_init() undoes its own failures */
+	bool init_unwinds;
+
 	/* rate limit the snapshot capture to once per attach */
 	atomic_t fault_snapshot_capture;
 

-- 
2.47.3