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Michael tried to enable Advanced Error Reporting through the ENETC's
Root Complex Event Collector, and the system started spitting out single
bit correctable ECC errors coming from the ENETC interfaces:

pcieport 0000:00:1f.0: AER: Multiple Corrected error received: 0000:00:00.0
fsl_enetc 0000:00:00.0: PCIe Bus Error: severity=Corrected, type=Transaction Layer, (Receiver ID)
fsl_enetc 0000:00:00.0:   device [1957:e100] error status/mask=00004000/00000000
fsl_enetc 0000:00:00.0:    [14] CorrIntErr
fsl_enetc 0000:00:00.1: PCIe Bus Error: severity=Corrected, type=Transaction Layer, (Receiver ID)
fsl_enetc 0000:00:00.1:   device [1957:e100] error status/mask=00004000/00000000
fsl_enetc 0000:00:00.1:    [14] CorrIntErr

Further investigating the port correctable memory error detect register
(PCMEDR) shows that these AER errors have an associated SOURCE_ID of 6
(RFS/RSS):

$ devmem 0x1f8010e10 32
0xC0000006
$ devmem 0x1f8050e10 32
0xC0000006

Discussion with the hardware design engineers reveals that on LS1028A,
the hardware does not do initialization of that RFS/RSS memory, and that
software should clear/initialize the entire table before starting to
operate. That comes as a bit of a surprise, since the driver does not do
initialization of the RFS memory. Also, the initialization of the
Receive Side Scaling is done only partially.

Even though the entire ENETC IP has a single shared flow steering
memory, the flow steering service should returns matches only for TCAM
entries that are within the range of the Station Interface that is doing
the search. Therefore, it should be sufficient for a Station Interface
to initialize all of its own entries in order to avoid any ECC errors,
and only the Station Interfaces in use should need initialization.

There are Physical Station Interfaces associated with PCIe PFs and
Virtual Station Interfaces associated with PCIe VFs. We let the PF
driver initialize the entire port's memory, which includes the RFS
entries which are going to be used by the VF.
Reported-by: Michael Walle <michael@walle.cc>
Fixes: d4fd0404

 ("enetc: Introduce basic PF and VF ENETC ethernet drivers")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Michael Walle <michael@walle.cc>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Link: https://lore.kernel.org/r/20210204134511.2640309-1-vladimir.oltean@nxp.com

Signed-off-by: Jakub Kicinski <kuba@kernel.org>