Re: [PATCH net-next] net: dsa: mv88e6xxx: Allow dynamic reconfiguration of tag protocol
From: Vladimir Oltean <olteanv@gmail.com>
Date: 2021-03-24 13:25:06
On Wed, Mar 24, 2021 at 02:01:14PM +0100, Tobias Waldekranz wrote:
On Wed, Mar 24, 2021 at 13:34, Vladimir Oltean [off-list ref] wrote:quoted
On Wed, Mar 24, 2021 at 11:52:49AM +0100, Tobias Waldekranz wrote:quoted
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This is the tragedy: I know for a fact that a DSA soft parser exists, but because of the aforementioned maze of NDAs and license agreements we, the community, cannot have nice things.Oh yeah? You can even create your own, if you have nerves of steel and a thick enough skin to learn to use the "fmc" (Frame Manager Configuration Tool) program, which is fully open source if you search for it on CAF (and if you can actually make something out of the source code).Yes, this is what a colleague of mine has done. Which is how I know that one exists :)quoted
And this PDF (hidden so well behind the maze of NDAs, that I just had to google for it, and you don't even need to register to read it): https://www.nxp.com/docs/en/user-guide/LSDKUG_Rev20.12.pdf is chock full of information on what you can do with it, see chapters 8.2.5 and 8.2.6.Right, but this is where it ends. Using the wealth of information you have laid out so far you can use DPAA to do amazing things using open components. ...unless you have to do something so incredibly advanced and exotic as a masked update of a field. At this point you have two options: 1. Buy the firmware toolchain, which requires signing an NDA. 2. Buy a single-drop firmware binary for lots of $$$ without any possibility of getting further updates because "you should really be using DPAA2".Uhm, what? By "firmware" I assume you mean "FMan microcode"? To my knowledge, the standard FMan microcode distributed _freely_ with the LSDK has support for Header Manipulation, you just need to create a Header Manipulation Command Descriptor (HMCD) and pass it to the microcode through an O/H port. I believe that: (a) the Header Manipulation descriptors allow you to perform raw mask based field updates too, not just for standard protocolsThis is not the story we were told.
Wait, aren't we talking about HdrMan OPCODE 0x19 ("Replace Field in Header")?
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(b) fmc already has some support for sending Header Manipulation descriptors to the microcode And by "firmware toolchain" you mean the FMan microcode SDK? https://www.nxp.com/design/software/embedded-software/linux-software-and-development-tools/dpaa-fman-microcode-sdk-source-code-software-kit:DPAA-FMAN-SDK In the description for that product it says: For MOST of NXP communications customers, the microcode that is freely accessible via the NXP LSDK or SDK for QorIQ or Layerscape processors will handle any communications offload task you could throw at the DPAA. So why on earth would you need that? And does it really surprise youBecause NXP said we needed it.quoted
that it costs money, especially considering the fact that you're going to need heaps of support for it anyway?No, it surprised me that we had to pay for a solution to a problem that we were promised would be solvable using the stock firmware.
Maybe the FMan version of your particular device does not support that HM command, or maybe you needed a slightly different behavior compared to what HM opcode 0x19 does, and there was a misunderstanding on either ends resulting in the impression that what you need could be achievable through that type of descriptor? Either way, the way you phrased things: | unless you have to do something so incredibly advanced and exotic as | a masked update of a field is very unfair, oversimplifying and misleading.
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Seriously, what is your point? You're complaining about having the option to write your own microcode for the RISC cores inside the network controller, when the standard one already comes with a lot of features? What would you prefer, not having that option? This is a strawman. None of the features we talked about in this thread, soft parser for DSA tags or masked header manipulation, should require custom microcode.I never made that claim. I was describing our experience with DPAA on the whole.
I fail to see how we ended up talking about custom FMan microcode then. I did not bring it up, and it is completely irrelevant to the discussion about soft parser for DSA.