• Frederic Barrat's avatar
    powerpc/powernv: Capture actag information for the device · 2cb3d64b
    Frederic Barrat authored
    In the opencapi protocol, host memory contexts are referenced by a
    'actag'. During setup, a driver must tell the device how many actags
    it can used, and what values are acceptable.
    
    On POWER9, the NPU can handle 64 actags per link, so they must be
    shared between all the PCI functions of the link. To get a global
    picture of how many actags are used by each AFU of every function, we
    capture some data at the end of PCI enumeration, so that actags can be
    shared fairly if needed.
    
    This is not powernv specific per say, but rather a consequence of the
    opencapi configuration specification being quite general. The number
    of available actags on POWER9 makes it more likely to be hit. This is
    somewhat mitigated by the fact that existing AFUs are coded by
    requesting a reasonable count of actags and existing devices carry
    only one AFU.
    Signed-off-by: default avatarFrederic Barrat <fbarrat@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    2cb3d64b
ocxl.c 12.5 KB