Re: [PATCH v4 net-next 7/8] net: mscc: ocelot: use index to set vcap policer

On Thu, Sep 23, 2021 at 09:30:59AM +0200, Horatiu Vultur wrote:

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In commit commit b596229448dd ("net: mscc: ocelot: Add support for tcam"), Horatiu Vultur define the max number of policers as 383:
+#define OCELOT_POLICER_DISCARD 0x17f
VCAP IS2 use this policer to set drop action. I did not change this and set the VCAP policers with 128-191 according to the VSC7514 document.

I don't know why 383 was used as the maximum value of policer in the original code. Can Microchip people check the code or the documentation for errors?

It was defined as 383 because the HW actually support this number of
policers. But for this SKU it is recomended to use 191, but no one will
stop you from using 383.

So if it is recommended to use 191, why did you use 383? Should Xiaoliang
change that to 191, or leave it alone?

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Also, FWIW, Seville has this policer allocation:

      0 ----+----------------------+
            |  Port Policers (11)  |
     11 ----+----------------------+
            |  VCAP Policers (21)  |
     32 ----+----------------------+
            |   QoS Policers (88)  |
    120 ----+----------------------+
            |  VCAP Policers (43)  |
    162 ----+----------------------+

I didn't find Seville's document, if this allocation is right, I will add it in Seville driver.

Strange enough, I don't remember having reports about the VCAP IS2
policers on Seville not working, and of course being in the common code,
we'd start with a count of 384 policers for that hardware too, and
counting from the end. I think I even tested the policers when adding
the VCAP IS2 constants, and they worked. Is there any sort of index
wraparound that takes place?