| Message ID | 20210415092610.953134-1-tobias@waldekranz.com |
|---|---|
| Headers | show |
| Series | net: dsa: Allow default tag protocol to be overridden from DT | expand |
On Thu, Apr 15, 2021 at 11:26:07AM +0200, Tobias Waldekranz wrote: > For devices that supports both regular and Ethertyped DSA tags, allow > the user to change the protocol. > > Additionally, because there are ethernet controllers that do not > handle regular DSA tags in all cases, also allow the protocol to be > changed on devices with undocumented support for EDSA. But, in those > cases, make sure to log the fact that an undocumented feature has been > enabled. > > Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> > --- Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
On 4/15/2021 2:26 AM, Tobias Waldekranz wrote: > All devices are capable of using regular DSA tags. Support for > Ethertyped DSA tags sort into three categories: > > 1. No support. Older chips fall into this category. > > 2. Full support. Datasheet explicitly supports configuring the CPU > port to receive FORWARDs with a DSA tag. > > 3. Undocumented support. Datasheet lists the configuration from > category 2 as "reserved for future use", but does empirically > behave like a category 2 device. > > So, instead of listing the one true protocol that should be used by a > particular chip, specify the level of support for EDSA (support for > regular DSA is implicit on all chips). As before, we use EDSA for all > chips that fully supports it. > > In upcoming changes, we will use this information to support > dynamically changing the tag protocol. > > Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
This is a continuation of the work started in this patch: https://lore.kernel.org/netdev/20210323102326.3677940-1-tobias@waldekranz.com/ In addition to the mv88e6xxx support to dynamically change the protocol, it is now possible to override the protocol from the device tree. This means that when a board vendor finds an incompatibility, they can specify a working protocol in the DT, and users will not have to worry about it. Some background information: In a system using an NXP T1023 SoC connected to a 6390X switch, we noticed that TO_CPU frames where not reaching the CPU. This only happened on hardware port 8. Looking at the DSA master interface (dpaa-ethernet) we could see that an Rx error counter was bumped at the same rate. The logs indicated a parser error. It just so happens that a TO_CPU coming in on device 0, port 8, will result in the first two bytes of the DSA tag being one of: 00 40 00 44 00 46 My guess was that since these values looked like 802.3 length fields, the controller's parser would signal an error if the frame length did not match what was in the header. This was later confirmed using two different workarounds provided by Vladimir. Unfortunately these either bypass or ignore the hardware parser and thus robs working combinations of the ability to do RSS and other nifty things. It was therefore decided to go with the option of a DT override. v1 -> v2: - Fail if the device does not support changing protocols instead of falling back to the default. (Andrew) - Only call change_tag_protocol on CPU ports. (Andrew/Vladimir) - Only allow changing the protocol on chips that have at least "undocumented" level of support for EDSA. (Andrew). - List the supported protocols in the binding documentation. I opted for only listing the protocols that I have tested. As more people test their drivers, they can add them. (Rob) I did not change the property name, as I am not sure which vendor prefix to use (if any). Since there is an existing "dsa,member" property, "dsa" seemed reasonable. Tobias Waldekranz (5): net: dsa: mv88e6xxx: Mark chips with undocumented EDSA tag support net: dsa: mv88e6xxx: Allow dynamic reconfiguration of tag protocol net: dsa: Only notify CPU ports of changes to the tag protocol net: dsa: Allow default tag protocol to be overridden from DT dt-bindings: net: dsa: Document dsa,tag-protocol property .../devicetree/bindings/net/dsa/dsa.yaml | 9 ++ drivers/net/dsa/mv88e6xxx/chip.c | 99 ++++++++++++------- drivers/net/dsa/mv88e6xxx/chip.h | 21 +++- include/net/dsa.h | 5 + net/dsa/dsa2.c | 95 ++++++++++++++---- net/dsa/switch.c | 25 ++--- 6 files changed, 184 insertions(+), 70 deletions(-)