[PATCH v2] drm/xe: Don't fail probe on unsupported mailbox command

[Raag Jadav]

If the device is running older pcode firmware, it is possible that newer
mailbox commands are not supported by it. The sysfs attributes aren't
useful in that case, but we shouldn't fail driver probe because of it.
As of now, it is unknown if we can distinguish unsupported commands before
attempting them. But until we figure out a way to do that, fix the
regressions.

v2: Add debug message (Lucas)

Fixes: cdc36b66cd41 ("drm/xe: Expose fan control and voltage regulator version")
Signed-off-by: Raag Jadav <raag.jadav at intel.com>
Tested-by: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/xe/xe_device_sysfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_device_sysfs.c b/drivers/gpu/drm/xe/xe_device_sysfs.c
index 8250aa4620ee..fd2ba0da02a2 100644
--- a/drivers/gpu/drm/xe/xe_device_sysfs.c
+++ b/drivers/gpu/drm/xe/xe_device_sysfs.c
@@ -160,8 +160,13 @@ static int late_bind_create_files(struct device *dev)
 
 	ret = xe_pcode_read(root, PCODE_MBOX(PCODE_LATE_BINDING, GET_CAPABILITY_STATUS, 0),
 			    &cap, NULL);
-	if (ret)
+	if (ret) {
+		if (ret == -ENXIO) {
+			drm_dbg(&xe->drm, "Late binding not supported by firmware\n");
+			ret = 0;
+		}
 		goto out;
+	}
 
 	if (REG_FIELD_GET(V1_FAN_SUPPORTED, cap)) {
 		ret = sysfs_create_file(&dev->kobj, &dev_attr_lb_fan_control_version.attr);
-- 
2.34.1