On Fri, 19 Nov 2021 16:02:43 -0800
Ben Widawsky <ben.widawsky@xxxxxxxxx> wrote:
> The PCIe device DVSEC, defined in the CXL 2.0 spec, 8.1.3 is required to
> be implemented by CXL 2.0 endpoint devices. Since the information
> contained within this DVSEC will be critically important for region
> configuration, it makes sense to find the value early.
>
> Since this DVSEC is not strictly required for mailbox functionality,
> failure to find this information does not result in the driver failing
> to bind.
That feels like a path we are going to forget to test sometime in the
future. Given it's a specification requirement, I'd treat it as
an error and make our lives easier going forwards!
Otherwise looks good to me.
>
> Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
> ---
> drivers/cxl/cxlmem.h | 2 ++
> drivers/cxl/pci.c | 7 +++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 8d96d009ad90..3ef3c652599e 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -98,6 +98,7 @@ struct cxl_mbox_cmd {
> *
> * @dev: The device associated with this CXL state
> * @regs: Parsed register blocks
> + * @device_dvsec: Offset to the PCIe device DVSEC
> * @payload_size: Size of space for payload
> * (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
> * @lsa_size: Size of Label Storage Area
> @@ -125,6 +126,7 @@ struct cxl_dev_state {
> struct device *dev;
>
> struct cxl_regs regs;
> + int device_dvsec;
>
> size_t payload_size;
> size_t lsa_size;
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index d2c743a31b0c..f3872cbee7f8 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -474,6 +474,13 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> if (IS_ERR(cxlds))
> return PTR_ERR(cxlds);
>
> + cxlds->device_dvsec = pci_find_dvsec_capability(pdev,
> + PCI_DVSEC_VENDOR_ID_CXL,
> + CXL_DVSEC_PCIE_DEVICE);
> + if (!cxlds->device_dvsec)
> + dev_warn(&pdev->dev,
> + "Device DVSEC not present. Expect limited functionality.\n");
> +
> rc = cxl_setup_regs(pdev, CXL_REGLOC_RBI_MEMDEV, &map);
> if (rc)
> return rc;
