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Subject[PATCH V10 8/9] cxl/port: Retry reading CDAT on failure
Date
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.

Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from V9
Alison Schofield/Davidlohr Bueso
Print debug on each iteration and error only after failure

Changes from V8
Move code to cxl/core/pci.c

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/core/pci.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 73e28b82ffcf..e68f13e66fcf 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -631,20 +631,18 @@ static int cxl_cdat_read_table(struct cxl_port *port,
return rc;
}

-void read_cdat_data(struct cxl_port *port)
+static int __read_cdat_data(struct cxl_port *port)
{
struct device *dev = &port->dev;
size_t cdat_length;
int ret;

if (cxl_cdat_get_length(port, &cdat_length))
- return;
+ return 0;

port->cdat.table = devm_kzalloc(dev, cdat_length, GFP_KERNEL);
- if (!port->cdat.table) {
- ret = -ENOMEM;
- goto error;
- }
+ if (!port->cdat.table)
+ return -ENOMEM;

port->cdat.length = cdat_length;
ret = cxl_cdat_read_table(port, &port->cdat);
@@ -652,12 +650,26 @@ void read_cdat_data(struct cxl_port *port)
devm_kfree(dev, port->cdat.table);
port->cdat.table = NULL;
port->cdat.length = 0;
- ret = -EIO;
- goto error;
+ return -EIO;
}

- return;
-error:
- dev_err(dev, "CDAT data read error (%d)\n", ret);
+ return 0;
+}
+
+void read_cdat_data(struct cxl_port *port)
+{
+ int retries = 5;
+ int rc;
+
+ while (retries--) {
+ rc = __read_cdat_data(port);
+ if (!rc)
+ return;
+ dev_dbg(&port->dev,
+ "CDAT data read error rc=%d (retries %d)\n",
+ rc, retries);
+ }
+ dev_err(&port->dev, "CDAT data read failed after %d retries\n",
+ retries);
}
EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);
--
2.35.1
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