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

Jonathan Cameron
2022-04-27T17:57:50Z

On Thu, 14 Apr 2022 13:32:36 -0700
ira.weiny@intel.com wrote:

> 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

validated, retry if the CDAT read fails.

> fails. For now 5 retries are implemented.
>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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);
>