Hi On Wed, Jun 17, 2020 at 4:06 PM Linus Walleij <linus.wall...@linaro.org> wrote: > > On Thu, Jun 4, 2020 at 1:23 PM Vladimir Oltean <olte...@gmail.com> wrote: > > > In the code you pointed to, there is a potentially relevant comment: > > > > 1532//CPU tag: Realtek Ethertype==0x8899(2 bytes)+protocol==0x9(4 > > MSB)+priority(2 bits)+reserved(4 bits)+portmask(6 LSB) > > > > https://svn.dd-wrt.com/browser/src/linux/universal/linux-3.2/drivers/net/ethernet/raeth/rb/rtl_multicast_snooping.c#L1527 > > https://svn.dd-wrt.com/browser/src/linux/universal/linux-3.2/drivers/net/ethernet/raeth/rb/rtl_multicast_snooping.c#L5224 > > > > This strongly indicates to me that the insertion tag is the same as > > the extraction tag. > > This code is a problem because it is Realtek-development style. > This style seems to be that the hardware people write the drivers > using copy/paste from the previous ASIC and ship is as soon as > possible. Keep this in mind. > > The above tag is using protocol 9 and is actually even documented > in a PDF I have for RTL8306. The problem is that the RTL8366RB > (I suspect also RTL8366S) uses protocol "a" (as in hex 10). > Which is of course necessarily different. > > I have *really* tried to figure out how the bits in protocol a works > when transmissing from the CPU port to any switch port. > > When nothing else worked, I just tried all bit combinations with > 0xannp where a is protocol and p is port. I looped through all > values several times trying to get a response from ping.
Have you looped through the whole 32-bit field? > > So this is really how far I can get right now, even with brute > force. > > > It is completely opaque to me why in patch "[net-next PATCH 2/5] net: > > dsa: rtl8366rb: Support the CPU DSA tag" you are _disabling_ the > > injection of these tags via RTL8368RB_CPU_INSTAG. I think it's natural > > that the switch drops these packets when CPU tag insertion is > > disabled. > > This is another Realtek-ism where they managed to invert the > meaning of a bit. > > Bit 15 in register 0x0061 (RTL8368RB_CPU_CTRL_REG) can > be set to 1 and then the special (custom) CPU tag 0x8899 > protocol a will be DISABLED. This value Realtek calls > "RTL8368RB_CPU_INSTAG" which makes you think that > the tag will be inserted, it is named "instag" right? But that > is not how it works. > > That bit needs to be set to 0 to insert the tag and 1 to disable > insertion of the tag. > > For this reason the patch also renames this bit to > RTL8368RB_CPU_NO_TAG which is more to the point. > > Yours, > Linus Walleij
