[PATCH 2/5] lib/xe: add xe_engine_class_supports_multi_lrc()

Xin Wang
2026-04-03T01:41:14Z

Add xe_engine_class_supports_multi_lrc() to query whether an engine
class supports multi-LRC submission. When the kernel exposes the
information via the debugfs info node it is used directly; otherwise
fall back to a hardcoded default to keep compatibility with older KMD.

Signed-off-by: Xin Wang <x.wang@intel.com>
---
lib/xe/xe_query.c | 30 ++++++++++++++++++++++++++++++
lib/xe/xe_query.h | 1 +
2 files changed, 31 insertions(+)

diff --git a/lib/xe/xe_query.c b/lib/xe/xe_query.c
index 441e95794..e13d5e143 100644
--- a/lib/xe/xe_query.c
+++ b/lib/xe/xe_query.c
@@ -308,6 +308,36 @@ static struct xe_device *find_in_cache(int fd)
return xe_dev;
}

+/**
+ * xe_engine_class_supports_multi_lrc:
+ * @fd: xe device fd
+ * @engine_class: engine class
+ *
+ * Returns true if multi LRC supported by engine class or false.
+ * Uses the kernel-reported bitmask from debugfs when available, otherwise
+ * falls back to the hardcoded per-class default.
+ */
+bool xe_engine_class_supports_multi_lrc(int fd, uint32_t engine_class)
+{
+ struct xe_device *xe_dev = find_in_cache(fd);
+
+ if (xe_dev && xe_dev->multi_lrc_mask != UINT16_MAX)
+ return !!(xe_dev->multi_lrc_mask & BIT(engine_class));
+
+ switch (engine_class) {
+ case DRM_XE_ENGINE_CLASS_COPY:
+ case DRM_XE_ENGINE_CLASS_COMPUTE:
+ case DRM_XE_ENGINE_CLASS_RENDER:
+ return false;
+ case DRM_XE_ENGINE_CLASS_VIDEO_DECODE:
+ case DRM_XE_ENGINE_CLASS_VIDEO_ENHANCE:
+ return true;
+ default:
+ igt_warn("Engine class 0x%x unknown\n", engine_class);
+ return false;
+ }
+}
+
static void xe_device_free(struct xe_device *xe_dev)
{
free(xe_dev->config);
diff --git a/lib/xe/xe_query.h b/lib/xe/xe_query.h
index f33562bda..5c26a3e88 100644
--- a/lib/xe/xe_query.h
+++ b/lib/xe/xe_query.h
@@ -162,6 +162,7 @@ uint32_t xe_va_bits(int fd);
uint16_t xe_dev_id(int fd);
int xe_supports_faults(int fd);
bool xe_engine_class_supports_multi_queue(uint32_t engine_class);
+bool xe_engine_class_supports_multi_lrc(int fd, uint32_t engine_class);
const char *xe_engine_class_string(uint32_t engine_class);
const char *xe_engine_class_short_string(uint32_t engine_class);
bool xe_has_engine_class(int fd, uint16_t engine_class);
--
2.43.0