eth: fbnic: Make Rx completion coalescing configurable

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The Rx completion queue writeback coalescing window controls how long
the queue manager may defer writing completions to host memory.

Expose this window through the standard rx-cqe-nsecs ethtool
parameter. Preserve the existing 2000 ns default and accept values
from 1000 ns through the device maximum (~109 us).

Hardware expresses COAL_WAIT in 600 MHz core clock cycles, or 1.667 ns
per cycle. Programming rounds the configured value to the nearest clock
cycle, resulting in an error of less than 1 ns. Retain the requested
value for get_coalesce() because this error is below the one-nanosecond
resolution of the ethtool interface.

Signed-off-by: Mohsin Bashir <hmohsin@meta.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260909211111.1795726-1-mohsin.bashr@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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This commit is contained in:

Mohsin Bashir 2026-09-09 14:11:11 -07:00 • committed by Jakub Kicinski

parent 57ca800cd3

commit c0aca269ec

6 changed files with 46 additions and 9 deletions

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2

drivers/net/ethernet/meta/fbnic/fbnic.h

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2

drivers/net/ethernet/meta/fbnic/fbnic_devlink.c

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15

drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c

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9

drivers/net/ethernet/meta/fbnic/fbnic_mac.c

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drivers/net/ethernet/meta/fbnic/fbnic_txrx.c

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10

drivers/net/ethernet/meta/fbnic/fbnic_txrx.h

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