There can be multiple reasons for a failure in atomic_ioctl. Most often
in these error conditions -EINVAL is returned. User/Compositor would
have to blindly take a call on failure of this ioctl so as to use
ALLOW_MODESET or any. It would be good if user/compositor gets a
readable error code on failure so they can take proper corrections in
the next commit.
The struct drm_mode_atomic is being passed by the user/compositor which
holds the properties for modeset/flip. Reusing the same struct for
returning the error code in case of failure can save by creating a new
uapi/interface for returning the error code.
There is an element reserved in the struct drm_mode_atomic which can be
used to return the user readable error code.
Here an effort is made using this reserved variable to return the error
code.
This is incomplete, just a start with returning few error codes have
been made. New flags can be added accordingly. Its a 64bit variable and
should suffice 64 error codes and should be sufficient.
Signed-off-by: Arun R Murthy <arun.r.mur...@intel.com>
---
drivers/gpu/drm/drm_atomic.c | 5 +++++
drivers/gpu/drm/drm_atomic_uapi.c | 17 ++++++++++++-----
include/drm/drm_atomic.h | 7 +++++++
include/uapi/drm/drm_mode.h | 28 ++++++++++++++++++++++++++++
4 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index
cd15cf52f0c9144711da5879da57884674aea9e4..0cf73022955437260d138c6a1e2bb9a8a4eca2f0
100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1513,6 +1513,8 @@ int drm_atomic_check_only(struct drm_atomic_state *state)
if (drm_atomic_crtc_needs_modeset(new_crtc_state)) {
drm_dbg_atomic(dev, "[CRTC:%d:%s] requires full
modeset\n",
crtc->base.id, crtc->name);
+ state->error_code =
DRM_MODE_ATOMIC_CRTC_NEED_FULL_MODESET;
+
return -EINVAL;
}
}
@@ -1537,8 +1539,11 @@ int drm_atomic_check_only(struct drm_atomic_state *state)
drm_dbg_atomic(dev,
"driver added CRTC to commit: requested 0x%x,
affected 0x%0x\n",
requested_crtc, affected_crtc);
+ state->error_code = DRM_MODE_ATOMIC_NEED_FULL_MODESET;
WARN(!state->allow_modeset, "adding CRTC not allowed without
modesets: requested 0x%x, affected 0x%0x\n",
requested_crtc, affected_crtc);
+
+ return -EINVAL;
}
return 0;
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c
b/drivers/gpu/drm/drm_atomic_uapi.c
index
ecc73d52bfae41a7ef455a7e13649ec56c690b90..ff711c8d6ef204c1e50c6bb506af6f5adb4d9b4e
100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1400,6 +1400,11 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
return -EOPNOTSUPP;
+ if (arg->reserved) {
+ drm_dbg_atomic(dev, "commit failed: reserved field set\n");
+ return -EINVAL;
+ }
+
/* disallow for userspace that has not enabled atomic cap (even
* though this may be a bit overkill, since legacy userspace
* wouldn't know how to call this ioctl)
@@ -1407,16 +1412,13 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
if (!file_priv->atomic) {
drm_dbg_atomic(dev,
"commit failed: atomic cap not enabled\n");
+ arg->reserved = DRM_MODE_ATOMIC_CAP_NOT_ENABLED;
return -EINVAL;
}
if (arg->flags & ~DRM_MODE_ATOMIC_FLAGS) {
drm_dbg_atomic(dev, "commit failed: invalid flag\n");
- return -EINVAL;
- }
-
- if (arg->reserved) {
- drm_dbg_atomic(dev, "commit failed: reserved field set\n");
+ arg->reserved = DRM_MODE_ATOMIC_INVALID_FLAG;
return -EINVAL;
}
@@ -1424,6 +1426,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
if (!dev->mode_config.async_page_flip) {
drm_dbg_atomic(dev,
"commit failed: DRM_MODE_PAGE_FLIP_ASYNC
not supported\n");
+ arg->reserved = DRM_MODE_ATOMIC_PAGE_FLIP_ASYNC;
return -EINVAL;
}
@@ -1435,6 +1438,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
(arg->flags & DRM_MODE_PAGE_FLIP_EVENT)) {
drm_dbg_atomic(dev,
"commit failed: page-flip event requested with
test-only commit\n");
+ arg->reserved = DRM_MODE_ATOMIC_FLIP_EVENT_WITH_CHECKONLY;
return -EINVAL;
}
@@ -1541,6 +1545,9 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
ret = drm_atomic_commit(state);
}
+ /* update the error code if any error to allow user handling it */
+ arg->reserved = state->error_code;
+
out:
complete_signaling(dev, state, fence_state, num_fences, !ret);
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index
38636a593c9d98cadda85ccd67326cb152f0dd27..55799d848408e23ae5ece2dd694d119489a87ede
100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -524,6 +524,13 @@ struct drm_atomic_state {
* commit without blocking.
*/
struct work_struct commit_work;
+
+ /* @error_code
+ *
+ * flag to convey user readable error to the user.
+ * Error codes defined in DRM_MODE_ATOMIC_ERR_FLAGS
+ */
+ u64 error_code;
};
void __drm_crtc_commit_free(struct kref *kref);
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index
c082810c08a8b234ef2672ecf54fc8c05ddc2bd3..dccf0e8a40cd06e89b0e016356d4fef89cd93a29
100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -1149,6 +1149,34 @@ struct drm_mode_destroy_dumb {
DRM_MODE_ATOMIC_NONBLOCK |\
DRM_MODE_ATOMIC_ALLOW_MODESET)
+/* atomic not set in the drm_file */
+#define DRM_MODE_ATOMIC_CAP_NOT_ENABLED BIT(0)
+/* atomic flag passed not in DRM_MODE_ATOMIC_FLAGS list */
+#define DRM_MODE_ATOMIC_INVALID_FLAG BIT(1)
+/* DRM_MODE_PAGE_FLIP_LEGACY not supported with atomic ioctl */
+#define DRM_MODE_ATOMIC_PAGE_FLIP_ASYNC BIT(2)
+/* flip event with atomic check only not supported */
+#define DRM_MODE_ATOMIC_FLIP_EVENT_WITH_CHECKONLY BIT(3)
+/* atomic property change requested need full crtc modeset */
+#define DRM_MODE_ATOMIC_CRTC_NEED_FULL_MODESET BIT(4)
+/* atomic property change requested has impact on all connected crtc */
+#define DRM_MODE_ATOMIC_NEED_FULL_MODESET BIT(5)
+
+/**
+ * DRM_MODE_ATOMIC_ERR_FLAGS
+ *
+ * Bit field of the reserved element in drm_mode_atomic will be
+ * used for returning meaningful error message to the compositor
+ * so that compositor can take necessary correction going ahead.
+ */
+#define DRM_MODE_ATOMIC_ERR_FLAGS (\
+ DRM_MODE_ATOMIC_CAP_NOT_ENABLED |\
+ DRM_MODE_ATOMIC_INVALID_FLAG |\
+ DRM_MODE_ATOMIC_PAGE_FLIP_ASYNC |\
+ DRM_MODE_ATOMIC_FLIP_EVENT_WITH_CHECKONLY |\
+ DRM_MODE_ATOMIC_CRTC_NEED_FULL_MODESET |\
+ DRM_MODE_ATOMIC_NEED_FULL_MODESET)
+
struct drm_mode_atomic {
__u32 flags;
__u32 count_objs;
---
base-commit: bd57aee20daefb7b0dfe9017663668c92115ff19
change-id: 20250625-atomic-ed735b97002f
Best regards,
--
Arun R Murthy <arun.r.mur...@intel.com>
