On 2026-06-05 at 12:02:44, Ratheesh Kannoth (rkannoth@marvell.com) wrote:

Default CN20K NPC rule allocation now keys off the active MCAM keyword
width: use X4 with a bank-masked reference index when the silicon uses
X4 keys, and X2 with the raw index otherwise (replacing the previous
always-X2 / eidx + 1 behaviour).

In the AF flow-install path, flows that need more than 256 key bits
query the NPC profile; if the platform is fixed to X2 entries, fail
with -EOPNOTSUPP instead of requesting X4. Otherwise select X4 for the
MCAM alloc.

On the PF, cache and pass the profile kw_type from npc_get_pfl_info
through otx2_mcam_pfl_info_get(), and use it when allocating MCAM
entries for RSS/defaults and when installing ethtool flows on CN20K,
including masking the reference index for X4 slot layout.

Signed-off-by: Ratheesh Kannoth <redacted>

https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260605063245.3553861-1-rkannoth%40marvell.com says

The commit message says this replaces the "previous always-X2 /
eidx + 1 behaviour", but the pre-patch code used ref_entry = eidx
in the higher-priority allocation and ref_entry = eidx + 1 only in
the VF lower-priority fallback path.
Is the commit message description of the prior behavior accurate?
For the lower-priority fallback in the X2 branch, ref_entry now becomes
eidx instead of eidx + 1, so the value passed to
rvu_mbox_handler_npc_mcam_alloc_entry() changes for already-shipping X2
CN20K silicon, separate from the X4 enablement.
Was the prior eidx + 1 a deliberate offset (for example to step past
the higher-priority slot reserved by the first allocation) or an
off-by-one that is being corrected here?
If it is a fix, would it make sense to split this into a standalone
patch with a Fixes: tag so it can be backported and bisected
independently of the X4 enablement, and could the rationale be added
to the changelog?

eidx is the oorrect value as eidx + 1 may overflow. initially i submitted this patch
as bug fix, but simon said this is more than a bug fix, so this is part of net-next.