cxl/pci: Add debug for DVSEC range init failures

In preparation for not treating DVSEC range initialization failures as
fatal to cxl_pci_probe() add individual dev_dbg() statements for each of
the major failure reasons in cxl_dvsec_ranges().

The rationale for cxl_dvsec_ranges() failure not being fatal is that
there is still value for cxl_pci to enable mailbox operations even if
CXL.mem operation is disabled.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/164730734812.3806189.2726330688692684104.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/pci.c

@@ -467,12 +467,15 @@ static int cxl_dvsec_ranges(struct cxl_dev_state *cxlds)
 {
 	struct cxl_endpoint_dvsec_info *info = &cxlds->info;
 	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
+	struct device *dev = &pdev->dev;
 	int d = cxlds->cxl_dvsec;
 	int hdm_count, rc, i;
 	u16 cap, ctrl;
 
-	if (!d)
+	if (!d) {
+		dev_dbg(dev, "No DVSEC Capability\n");
 		return -ENXIO;
+	}
 
 	rc = pci_read_config_word(pdev, d + CXL_DVSEC_CAP_OFFSET, &cap);
 	if (rc)
@@ -482,8 +485,10 @@ static int cxl_dvsec_ranges(struct cxl_dev_state *cxlds)
 	if (rc)
 		return rc;
 
-	if (!(cap & CXL_DVSEC_MEM_CAPABLE))
+	if (!(cap & CXL_DVSEC_MEM_CAPABLE)) {
+		dev_dbg(dev, "Not MEM Capable\n");
 		return -ENXIO;
+	}
 
 	/*
 	 * It is not allowed by spec for MEM.capable to be set and have 0 legacy
@@ -496,8 +501,10 @@ static int cxl_dvsec_ranges(struct cxl_dev_state *cxlds)
 		return -EINVAL;
 
 	rc = wait_for_valid(cxlds);
-	if (rc)
+	if (rc) {
+		dev_dbg(dev, "Failure awaiting MEM_INFO_VALID (%d)\n", rc);
 		return rc;
+	}
 
 	info->mem_enabled = FIELD_GET(CXL_DVSEC_MEM_ENABLE, ctrl);