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Subject[PATCH V9 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.

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

---
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 | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index bb370df1cb6c..7f7dac9030a6 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -620,20 +620,18 @@ 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);
@@ -641,12 +639,24 @@ 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)
+ break;
+ dev_err(&port->dev,
+ "CDAT data read error rc=%d (retries %d)\n",
+ rc, retries);
+ }
}
EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);
--
2.35.1
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