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

[Wu, Hao]

> -----Original Message-----
> From: matthew.gerlach@xxxxxxxxxxxxxxx <matthew.gerlach@xxxxxxxxxxxxxxx>
> Sent: Thursday, July 7, 2022 11:06 PM
> To: Wu, Hao <hao.wu@xxxxxxxxx>; Xu, Yilun <yilun.xu@xxxxxxxxx>; Weight,
> Russell H <russell.h.weight@xxxxxxxxx>; Muddebihal, Basheer Ahmed
> <basheer.ahmed.muddebihal@xxxxxxxxx>; trix@xxxxxxxxxx;
> mdf@xxxxxxxxxx; corbet@xxxxxxx; linux-fpga@xxxxxxxxxxxxxxx; linux-
> doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Zhang, Tianfei
> <tianfei.zhang@xxxxxxxxx>
> Cc: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> Subject: [PATCH v3 1/2] Documentation: fpga: dfl: add PCI Identification
> documentation
> 
> 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.
>  https://github.com/OPAE/dfl-feature-id
> 
> 
> +PCI Device Identification
> +================================
> +Since FPGA based PCI cards can be reconfigured to a perform a completely
> +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 https://github.com/OPAE/dfl-feature-id/blob/main/dfl-pci-
> ids.rst.

I feel that we may not really need this in fpga-dfl doc, as this is not describing
any new method provided by DFL, but just something from PCI standard, right?

Thanks
Hao