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    Subject[PATCH 5.7 094/477] NTB: ntb_pingpong: Choose doorbells based on port number
    Date
    From: Logan Gunthorpe <logang@deltatee.com>

    [ Upstream commit ca93c45755da98302c93abdd788fc09113baf9e0 ]

    This commit fixes pingpong support for existing drivers that do not
    implement ntb_default_port_number() and ntb_default_peer_port_number().
    This is required for hardware (like the crosslink topology of
    switchtec) which cannot assign reasonable port numbers to each port due
    to its perfect symmetry.

    Instead of picking the doorbell to use based on the the index of the
    peer, we use the peer's port number. This is a bit clearer and easier
    to understand.

    Fixes: c7aeb0afdcc2 ("NTB: ntb_pp: Add full multi-port NTB API support")
    Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
    Acked-by: Allen Hubbe <allenbh@gmail.com>
    Tested-by: Alexander Fomichev <fomichev.ru@gmail.com>
    Signed-off-by: Jon Mason <jdmason@kudzu.us>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/ntb/test/ntb_pingpong.c | 14 ++++++--------
    1 file changed, 6 insertions(+), 8 deletions(-)

    diff --git a/drivers/ntb/test/ntb_pingpong.c b/drivers/ntb/test/ntb_pingpong.c
    index 04dd46647db36..2164e8492772d 100644
    --- a/drivers/ntb/test/ntb_pingpong.c
    +++ b/drivers/ntb/test/ntb_pingpong.c
    @@ -121,15 +121,14 @@ static int pp_find_next_peer(struct pp_ctx *pp)
    link = ntb_link_is_up(pp->ntb, NULL, NULL);

    /* Find next available peer */
    - if (link & pp->nmask) {
    + if (link & pp->nmask)
    pidx = __ffs64(link & pp->nmask);
    - out_db = BIT_ULL(pidx + 1);
    - } else if (link & pp->pmask) {
    + else if (link & pp->pmask)
    pidx = __ffs64(link & pp->pmask);
    - out_db = BIT_ULL(pidx);
    - } else {
    + else
    return -ENODEV;
    - }
    +
    + out_db = BIT_ULL(ntb_peer_port_number(pp->ntb, pidx));

    spin_lock(&pp->lock);
    pp->out_pidx = pidx;
    @@ -303,7 +302,7 @@ static void pp_init_flds(struct pp_ctx *pp)
    break;
    }

    - pp->in_db = BIT_ULL(pidx);
    + pp->in_db = BIT_ULL(lport);
    pp->pmask = GENMASK_ULL(pidx, 0) >> 1;
    pp->nmask = GENMASK_ULL(pcnt - 1, pidx);

    @@ -432,4 +431,3 @@ static void __exit pp_exit(void)
    debugfs_remove_recursive(pp_dbgfs_topdir);
    }
    module_exit(pp_exit);
    -
    --
    2.25.1


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