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.
The element 'reserved' in the struct drm_mode_atomic is used for
returning the user readable error code. This points to the struct
drm_mode_atomic_err_code. Failure reasons have been initialized in
DRM_MODE_ATOMIC_FAILURE_REASON.
Signed-off-by: Arun R Murthy <arun.r.mur...@intel.com>
---
include/uapi/drm/drm_mode.h | 42 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index
a122bea2559387576150236e3a88f99c24ad3138..f0986a3fe9a7d61e57e9a9a5ec01a604343f6930
100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -45,6 +45,7 @@ extern "C" {
#define DRM_CONNECTOR_NAME_LEN 32
#define DRM_DISPLAY_MODE_LEN 32
#define DRM_PROP_NAME_LEN 32
+#define DRM_MODE_ATOMIC_FAILURE_STRING_LEN 64
#define DRM_MODE_TYPE_BUILTIN (1<<0) /* deprecated */
#define DRM_MODE_TYPE_CLOCK_C ((1<<1) | DRM_MODE_TYPE_BUILTIN) /* deprecated
*/
@@ -1157,6 +1158,47 @@ struct drm_mode_destroy_dumb {
DRM_MODE_ATOMIC_NONBLOCK |\
DRM_MODE_ATOMIC_ALLOW_MODESET)
+#define DRM_MODE_ATOMIC_FAILURE_REASON \
+ FAILURE_REASON(DRM_MODE_ATOMIC_CAP_NOT_ENABLED, "DRM_ATOMIC capability
not enabled") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_INVALID_FLAG, "invalid flag") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_PAGE_FLIP_ASYNC, "Legacy
DRM_MODE_PAGE_FLIP_ASYNC not to be used in atomic ioctl") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_FLIP_EVENT_WITH_CHECKONLY, "requesting
page-flip event with TEST_ONLY") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_CRTC_NEED_FULL_MODESET, "Need full
modeset on this crtc") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_NEED_FULL_MODESET, "Need full modeset on
all the connected crtc's") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_ASYNC_NOT_SUP_PLANE, "Async flip not
supported on this plane") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_ASYNC_MODIFIER_NOT_SUPPORTED, "Modifier
not supported on this plane with async flip") \
+ FAILURE_REASON(DRM_MODE_ATOMIC_ASYNC_PROP_CHANGED, "No property change
allowed when async flip is enabled")
+
+#define FAILURE_REASON(flag, reason) flag,
+typedef enum {
+ DRM_MODE_ATOMIC_FAILURE_REASON
+} drm_mode_atomic_failure_flag;
+#undef FAILURE_REASON
+
+#define FAILURE_REASON(flag, reason) #reason,
+extern const char *drm_mode_atomic_failure_string[];
+#undef FAILURE_REASON
+
+/**
+ * drm_mode_atomic_err_code - struct to store the error code
+ *
+ * pointer to this struct will be stored in reserved variable of
+ * struct drm_mode_atomic to report the failure cause to the user.
+ *
+ * @failure_flags: error codes defined in drm_atomic_failure.failure_flag
+ * @failure_string_ptr: pointer to user readable error message
drm_mode_failure.failure_string
+ * @failure_obj_ptr: pointer to the drm_object that caused error
+ * @reserved: reserved for future use
+ * @count_objs: count of drm_objects if multiple drm_objects caused error
+ */
+struct drm_mode_atomic_err_code {
+ __u64 failure_flags;
+ __u64 failure_objs_ptr;
+ __u64 reserved;
+ __u32 count_objs;
+ char failure_string[DRM_MODE_ATOMIC_FAILURE_STRING_LEN];
+};
+
struct drm_mode_atomic {
__u32 flags;
__u32 count_objs;
--
2.25.1
