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

[Vladimir Oltean]

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

> > > 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?