When CONFIG_PROVE_LOCKING is defined, the kernel randomly injects
-EDEADLK errors for all the ww_mutex. This results in
drm_atomic_get_private_obj_state randomly returning -EDEADLK.
However, the mode_fixup functions do not propagate these error
codes and return false, causing the atomic commit to fail with
-EINVAL instead of retrying.

Change encoder, crtc, and bridge mode_fixup functions to return
an int instead of a boolean to indicate success or failure. If
any of these functions fail, the mode_fixup function now returns
the provided integer error code instead of -EINVAL.

This change needs modifications across drivers, but before submitting
the entire change, we want to get feedback on this RFC.

Signed-off-by: Grace An <gra...@codeaurora.org>
---
 drivers/gpu/drm/drm_atomic_helper.c      | 8 ++++----
 drivers/gpu/drm/drm_bridge.c             | 4 ++--
 include/drm/drm_bridge.h                 | 2 +-
 include/drm/drm_modeset_helper_vtables.h | 4 ++--
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c 
b/drivers/gpu/drm/drm_atomic_helper.c
index f2b3e28..d75f09a 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -457,10 +457,10 @@ mode_fixup(struct drm_atomic_state *state)
                } else if (funcs && funcs->mode_fixup) {
                        ret = funcs->mode_fixup(encoder, &new_crtc_state->mode,
                                                &new_crtc_state->adjusted_mode);
-                       if (!ret) {
+                       if (ret) {
                                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] fixup 
failed\n",
                                                 encoder->base.id, 
encoder->name);
-                               return -EINVAL;
+                               return ret;
                        }
                }
        }
@@ -481,10 +481,10 @@ mode_fixup(struct drm_atomic_state *state)
 
                ret = funcs->mode_fixup(crtc, &new_crtc_state->mode,
                                        &new_crtc_state->adjusted_mode);
-               if (!ret) {
+               if (ret) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] fixup failed\n",
                                         crtc->base.id, crtc->name);
-                       return -EINVAL;
+                       return ret;
                }
        }
 
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 64f0eff..3ad16b5 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -736,9 +736,9 @@ static int drm_atomic_bridge_check(struct drm_bridge 
*bridge,
                if (ret)
                        return ret;
        } else if (bridge->funcs->mode_fixup) {
-               if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
+               if (bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
                                               &crtc_state->adjusted_mode))
-                       return -EINVAL;
+                       return ret;
        }
 
        return 0;
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 2195daa..5d02dfc 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -153,7 +153,7 @@ struct drm_bridge_funcs {
         * True if an acceptable configuration is possible, false if the modeset
         * operation should be rejected.
         */
-       bool (*mode_fixup)(struct drm_bridge *bridge,
+       int (*mode_fixup)(struct drm_bridge *bridge,
                           const struct drm_display_mode *mode,
                           struct drm_display_mode *adjusted_mode);
        /**
diff --git a/include/drm/drm_modeset_helper_vtables.h 
b/include/drm/drm_modeset_helper_vtables.h
index f3a4b47..e305c97 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -184,7 +184,7 @@ struct drm_crtc_helper_funcs {
         * True if an acceptable configuration is possible, false if the modeset
         * operation should be rejected.
         */
-       bool (*mode_fixup)(struct drm_crtc *crtc,
+       int (*mode_fixup)(struct drm_crtc *crtc,
                           const struct drm_display_mode *mode,
                           struct drm_display_mode *adjusted_mode);
 
@@ -599,7 +599,7 @@ struct drm_encoder_helper_funcs {
         * True if an acceptable configuration is possible, false if the modeset
         * operation should be rejected.
         */
-       bool (*mode_fixup)(struct drm_encoder *encoder,
+       int (*mode_fixup)(struct drm_encoder *encoder,
                           const struct drm_display_mode *mode,
                           struct drm_display_mode *adjusted_mode);
 
-- 
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