Re: [PATCH v3 1/2] Documentation: fpga: dfl: add PCI Identification documentation

From: Marco Pagani
Date: Tue Jul 12 2022 - 13:14:46 EST

On 2022-07-07 17:05, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
> From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> Add documentation on identifying FPGA based PCI cards prompted
> by discussion on the linux-fpga@xxxxxxxxxxxxxxx mailing list.
> Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> ---
> v3: Add url to page tracking PCI ID information for DFL based cards.
> v2: Introduced in v2.
> ---
> Documentation/fpga/dfl.rst | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> index 15b670926084..5144775b860a 100644
> --- a/Documentation/fpga/dfl.rst
> +++ b/Documentation/fpga/dfl.rst
> @@ -507,6 +507,27 @@ ids application.
> +PCI Device Identification
> +================================
> +Since FPGA based PCI cards can be reconfigured to a perform a completely

There's a small typo: "to a perform" --> "to perform"

> +new function at runtime, properly identifying such cards and binding the
> +correct driver can be challenging. In many use cases, deployed FPGA based
> +PCI cards are essentially static and the PCI Product ID and Vendor ID pair
> +is sufficient to identify the card. The DFL framework helps with the
> +dynamic case of deployed FPGA cards changing at run time by providing
> +more detailed information about card discoverable at runtime.
> +
> +At one level, the DFL on a PCI card describes the function of the card.
> +However, the same DFL could be instantiated on different physical cards.
> +Conversely, different DFLs could be instantiated on the same physical card.
> +Practical management of a cloud containing a heterogeneous set of such cards
> +requires a PCI level of card identification. While the PCI Product ID and
> +Vendor ID may be sufficient to bind the dfl-pci driver, it is expected
> +that FPGA PCI cards would advertise suitable Subsystem ID and Subsystem
> +Vendor ID values. Further PCI Product, Vendor, and Subsystem id tracking
> +can be found at
> +
> +
> Location of DFLs on a PCI Device
> ================================
> The original method for finding a DFL on a PCI device assumed the start of the