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> --- v2: Introduced in v2. --- Documentation/fpga/dfl.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst index ef9eec71f6f3..5fb2ca8e76d7 100644 --- a/Documentation/fpga/dfl.rst +++ b/Documentation/fpga/dfl.rst @@ -502,6 +502,26 @@ Developer only needs to provide a sub feature driver with matched feature id. FME Partial Reconfiguration Sub Feature driver (see drivers/fpga/dfl-fme-pr.c) could be a reference. +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. PCI Vital Product Data (VPD) can also be used for +more granular information about the board. + Location of DFLs on a PCI Device ================================ The original method for finding a DFL on a PCI device assumed the start of the -- 2.25.1
