[PATCH 2/2] cxl: Set VPD timeout to avoid access failures

[Andrew Donnellan]

On 22/11/16 08:10, Matthew R. Ochs wrote:
> Some IBM CXL devices can take up to ~120ms to complete a VPD access

Which devices?

> transaction when under heavy load. With an existing default VPD timeout
> of 50ms, reads/writes can fail despite there not being an issue with the
> underlying hardware.
>
> To avoid these false failures, increase the VPD wait timeout for certain
> CXL devices to a value that allows appropriate VPD access delay when faced
> with a worst-case scenario.
>
> Signed-off-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>

Contingent on Bjorn applying patch 1, and with comment below:

Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

> ---
>  drivers/misc/cxl/pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
> index e96be9c..56a67cf 100644
> --- a/drivers/misc/cxl/pci.c
> +++ b/drivers/misc/cxl/pci.c
> @@ -1675,6 +1675,10 @@ bool cxl_slot_is_supported(struct pci_dev *dev, int flags)
>  }
>  EXPORT_SYMBOL_GPL(cxl_slot_is_supported);
>
> +static bool cxl_pci_is_slow_vpd_device(struct pci_dev *dev)
> +{
> +	return dev->device == 0x0601;

Comment with device name.

> +}
>
>  static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  {
> @@ -1692,6 +1696,9 @@ static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  		return -ENODEV;
>  	}
>
> +	if (cxl_pci_is_slow_vpd_device(dev))
> +		pci_set_vpd_timeout(dev, msecs_to_jiffies(125));
> +
>  	if (cxl_verbose)
>  		dump_cxl_config_space(dev);
>
>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited