On Wed, 20 Jan 2021 01:07:48 +0200 Vladimir Oltean wrote: > From: Vladimir Oltean <vladimir.olt...@nxp.com> > > Since the tag_8021q tagger is software-defined, it has no means by > itself for retrieving hardware timestamps of PTP event messages. > > Because we do want to support PTP on ocelot even with tag_8021q, we need > to use the CPU port module for that. The RX timestamp is present in the > Extraction Frame Header. And because we can't use NPI mode which redirects > the CPU queues to an "external CPU" (meaning the ARM CPU running Linux), > then we need to poll the CPU port module through the MMIO registers to > retrieve TX and RX timestamps. > > Sadly, on NXP LS1028A, the Felix switch was integrated into the SoC > without wiring the extraction IRQ line to the ARM GIC. So, if we want to > be notified of any PTP packets received on the CPU port module, we have > a problem. > > There is a possible workaround, which is to use the Ethernet CPU port as > a notification channel that packets are available on the CPU port module > as well. When a PTP packet is received by the DSA tagger (without timestamp, > of course), we go to the CPU extraction queues, poll for it there, then > we drop the original Ethernet packet and masquerade the packet retrieved > over MMIO (plus the timestamp) as the original when we inject it up the > stack. > > Create a quirk in struct felix is selected by the Felix driver (but not > by Seville, since that doesn't support PTP at all). We want to do this > such that the workaround is minimally invasive for future switches that > don't require this workaround. > > The only traffic for which we need timestamps is PTP traffic, so add a > redirection rule to the CPU port module for this. Currently we only have > the need for PTP over L2, so redirection rules for UDP ports 319 and 320 > are TBD for now. > > Note that for the workaround of matching of PTP-over-Ethernet-port with > PTP-over-MMIO queues to work properly, both channels need to be > absolutely lossless. There are two parts to achieving that: > - We keep flow control enabled on the tag_8021q CPU port > - We put the DSA master interface in promiscuous mode, so it will never > drop a PTP frame (for the profiles we are interested in, these are > sent to the multicast MAC addresses of 01-80-c2-00-00-0e and > 01-1b-19-00-00-00). > > Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com>
drivers/net/dsa/ocelot/felix.c:464:12: warning: variable ‘err’ set but not used [-Wunused-but-set-variable] 464 | int port, err; | ^~~ drivers/net/dsa/ocelot/felix.c:265:53: warning: incorrect type in assignment (different base types) drivers/net/dsa/ocelot/felix.c:265:53: expected unsigned short [usertype] drivers/net/dsa/ocelot/felix.c:265:53: got restricted __be16 [usertype] Please build test the patches locally, the patchwork testing thing is not keeping up with the volume, and it's running on the largest VM available thru the provider already :/ I need to add this "don't post your patches to get them build tested or you'll make Kuba very angry" to the netdev FAQ.