[PATCH V8 09/10] cxl/mem: Retry reading CDAT on failure

ira.weiny
2022-04-14T20:33:26Z

From: Ira Weiny <ira.weiny@intel.com>

The CDAT read may fail for a number of reasons but mainly it is possible
to get different parts of a valid state. The checksum in the CDAT table
protects against this.

Now that the cdat data is validated issue a retries if the CDAT read
fails. For now 5 retries are implemented.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from V6
Move to pci.c
Fix retries count
Change to 5 retries

Changes from V5:
New patch -- easy to push off or drop.
---
drivers/cxl/pci.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index d7952156dd02..43cbc297079d 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -940,7 +940,7 @@ static void cxl_initialize_cdat_callbacks(struct cxl_dev_state *cxlds)
cxlds->cdat_read_table = cxl_cdat_read_table;
}

-static int read_cdat_data(struct cxl_dev_state *cxlds)
+static int __read_cdat_data(struct cxl_dev_state *cxlds)
{
struct device *dev = cxlds->dev;
size_t cdat_length;
@@ -962,6 +962,21 @@ static int read_cdat_data(struct cxl_dev_state *cxlds)
return ret;
}

+static void read_cdat_data(struct cxl_dev_state *cxlds)
+{
+ int retries = 5;
+ int rc;
+
+ while (retries--) {
+ rc = __read_cdat_data(cxlds);
+ if (!rc)
+ break;
+ dev_err(cxlds->dev,
+ "CDAT data read error rc=%d (retries %d)\n",
+ rc, retries);
+ }
+}
+
static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct cxl_register_map map;
@@ -1035,9 +1050,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
cxl_initialize_cdat_callbacks(cxlds);

/* Cache the data early to ensure is_visible() works */
- rc = read_cdat_data(cxlds);
- if (rc)
- dev_err(&pdev->dev, "CDAT data read error (%d)\n", rc);
+ read_cdat_data(cxlds);

cxl_dvsec_ranges(cxlds);

--
2.35.1