Re: [PATCH v4 03/23] cxl: Add support for reading CXL switch CDAT table

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Wed, 19 Apr 2023 13:21:19 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Move read_cdat_data() from endpoint probe to general port probe to
> allow reading of CDAT data for CXL switches as well as CXL device.
> Add wrapper support for cxl_test to bypass the cdat reading.
> 
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

It might be worth a wrapper at somepoint for that dance
from port to the PCI device with the actual DOE etc.

Such a wrapp would provide somewhere to add a bit of
documentation on why the uport might be a platform device
(memX) or might be a PCI device thus explaining the two
different way it is handled.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> 
> ---
> v4:
> - Remove cxl_test wrapper. (Ira)
> ---
>  drivers/cxl/core/pci.c |   20 +++++++++++++++-----
>  drivers/cxl/port.c     |    6 +++---
>  2 files changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 9c7e2f69d9ca..1c415b26e866 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -546,16 +546,26 @@ static unsigned char cdat_checksum(void *buf, size_t size)
>   */
>  void read_cdat_data(struct cxl_port *port)
>  {
> -	struct pci_doe_mb *cdat_doe;
> -	struct device *dev = &port->dev;
>  	struct device *uport = port->uport;
> -	struct cxl_memdev *cxlmd = to_cxl_memdev(uport);
> -	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> -	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
> +	struct device *dev = &port->dev;
> +	struct cxl_dev_state *cxlds;
> +	struct pci_doe_mb *cdat_doe;
> +	struct cxl_memdev *cxlmd;
> +	struct pci_dev *pdev;
>  	size_t cdat_length;
>  	void *cdat_table;
>  	int rc;
>  
> +	if (is_cxl_memdev(uport)) {
> +		cxlmd = to_cxl_memdev(uport);
> +		cxlds = cxlmd->cxlds;          
> +		pdev = to_pci_dev(cxlds->dev); 
> +	} else if (dev_is_pci(uport)) {
> +		pdev = to_pci_dev(uport);
> +	} else {
> +		return;
> +	}
> +
>  	cdat_doe = pci_find_doe_mailbox(pdev, PCI_DVSEC_VENDOR_ID_CXL,
>  					CXL_DOE_PROTOCOL_TABLE_ACCESS);
>  	if (!cdat_doe) {
> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index 22a7ab2bae7c..615e0ef6b440 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c
> @@ -93,9 +93,6 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>  	if (IS_ERR(cxlhdm))
>  		return PTR_ERR(cxlhdm);
>  
> -	/* Cache the data early to ensure is_visible() works */
> -	read_cdat_data(port);
> -
>  	get_device(&cxlmd->dev);
>  	rc = devm_add_action_or_reset(&port->dev, schedule_detach, cxlmd);
>  	if (rc)
> @@ -135,6 +132,9 @@ static int cxl_port_probe(struct device *dev)
>  {
>  	struct cxl_port *port = to_cxl_port(dev);
>  
> +	/* Cache the data early to ensure is_visible() works */
> +	read_cdat_data(port);
> +
>  	if (is_cxl_endpoint(port))
>  		return cxl_endpoint_port_probe(port);
>  	return cxl_switch_port_probe(port);
> 
>