[PATCH v10 2/7] drm/atomic: Add error_code element in atomic_state

Arun R Murthy
2026-02-23T09:17:45Z

Now that a proper error code will be returned to the user on any failure
in atomic_ioctl() via struct drm_mode_atomic, add a new element
error_code in the struct drm_atomic_state so as to hold the error code
during the atomic_check() and atomic_commit() phases.
New function added to print the error message and fill the struct
err_code with proper error message and error code.

v5: Add a function for printing the error message and filling err_code
struct
v6: Replace drm_err with drm_dbg_atomic print
v6: Add keyword "commit failed" in dbg msg (Suraj)

Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
---
drivers/gpu/drm/drm_atomic.c | 31 +++++++++++++++++++++++++++++++
include/drm/drm_atomic.h | 10 ++++++++++
2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 04925166df989bcb30b111739aa4ed5c84f3a5ae..5fd5cc4da99cea51c06da3e5f5603d9c018d4600 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -2122,6 +2122,37 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p)
}
EXPORT_SYMBOL(drm_state_dump);

+/**
+ * drm_mode_atomic_add_error_msg - function to add error code and error string
+ *
+ * @err_code: pointer to struct drm_mode_atomic_err_code that stores the failure
+ * reason
+ * @failure_code: failure code in enum drm_mode_atomic_failure_codes
+ * @failure_string: failure reason string message
+ *
+ * Returns: void
+ */
+void drm_mode_atomic_add_error_msg(struct drm_mode_atomic_err_code *err_code,
+ __u64 failure_code, const char *format, ...)
+{
+ struct drm_atomic_state *state = container_of(err_code,
+ struct drm_atomic_state,
+ error_code);
+ va_list varg;
+ char *failure_string;
+
+ err_code->failure_code = failure_code;
+
+ va_start(varg, format);
+ failure_string = kvasprintf(GFP_ATOMIC, format, varg);
+
+ drm_dbg_atomic(state->dev, "Commit failed: %s\n", failure_string);
+ strscpy_pad(err_code->failure_string, failure_string,
+ sizeof(err_code->failure_string));
+ va_end(varg);
+}
+EXPORT_SYMBOL(drm_mode_atomic_add_error_msg);
+
#ifdef CONFIG_DEBUG_FS
static int drm_state_info(struct seq_file *m, void *data)
{
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 0b1b32bcd2bda1b92299fd369ba7c23b1c2d3dfa..e26e68a955d33c2f7caa50b89ccb7d66c2c430d8 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -646,6 +646,13 @@ struct drm_atomic_state {
* commit without blocking.
*/
struct work_struct commit_work;
+
+ /* @error_code: pointer to struct holding failure reason and string
+ *
+ * struct to convey user readable error to the user.
+ * Error codes defined in enum drm_mode_atomic_failure_flags
+ */
+ struct drm_mode_atomic_err_code error_code;
};

void __drm_crtc_commit_free(struct kref *kref);
@@ -1373,5 +1380,8 @@ drm_atomic_get_old_bridge_state(const struct drm_atomic_state *state,
struct drm_bridge_state *
drm_atomic_get_new_bridge_state(const struct drm_atomic_state *state,
struct drm_bridge *bridge);
+__printf(3, 4)
+void drm_mode_atomic_add_error_msg(struct drm_mode_atomic_err_code *err_code,
+ __u64 failure_code, const char *format, ...);

#endif /* DRM_ATOMIC_H_ */

--
2.25.1