libnvdimm, btt: add btt startup debug

Report the reason for btt probe failures when debug is enabled.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index f068b6513cd2..af09d6c26709 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1388,11 +1388,15 @@ int nvdimm_namespace_attach_btt(struct nd_namespace_common *ndns)
         struct btt *btt;
         size_t rawsize;
 
-        if (!nd_btt->uuid || !nd_btt->ndns || !nd_btt->lbasize)
+        if (!nd_btt->uuid || !nd_btt->ndns || !nd_btt->lbasize) {
+                dev_dbg(&nd_btt->dev, "incomplete btt configuration\n");
                 return -ENODEV;
+        }
 
         rawsize = nvdimm_namespace_capacity(ndns) - SZ_4K;
         if (rawsize < ARENA_MIN_SIZE) {
+                dev_dbg(&nd_btt->dev, "%s must be at least %ld bytes\n",
+                                dev_name(&ndns->dev), ARENA_MIN_SIZE + SZ_4K);
                 return -ENXIO;
         }
         nd_region = to_nd_region(nd_btt->dev.parent);