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

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Message-ID: <DB8PR04MB578599F04A8764034485CE89F0A39@DB8PR04MB5785.eurprd04.prod.outlook.com>
Date:   Thu, 23 Sep 2021 01:52:38 +0000
From:   Xiaoliang Yang <xiaoliang.yang_1@....com>
To:     Vladimir Oltean <vladimir.oltean@....com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "allan.nielsen@...rochip.com" <allan.nielsen@...rochip.com>,
        "joergen.andreasen@...rochip.com" <joergen.andreasen@...rochip.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        "vinicius.gomes@...el.com" <vinicius.gomes@...el.com>,
        "michael.chan@...adcom.com" <michael.chan@...adcom.com>,
        "vishal@...lsio.com" <vishal@...lsio.com>,
        "saeedm@...lanox.com" <saeedm@...lanox.com>,
        "jiri@...lanox.com" <jiri@...lanox.com>,
        "idosch@...lanox.com" <idosch@...lanox.com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "kuba@...nel.org" <kuba@...nel.org>, Po Liu <po.liu@....com>,
        Leo Li <leoyang.li@....com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "vivien.didelot@...il.com" <vivien.didelot@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>
Subject: RE: [PATCH v4 net-next 7/8] net: mscc: ocelot: use index to set vcap
 policer


On Wed, Sep 22, 2021 at 13:18:37 +0000, Vladimir Oltean wrote:
> > Policer was previously automatically assigned from the highest index
> > to the lowest index from policer pool. But police action of tc flower
> > now uses index to set an police entry. This patch uses the police
> > index to set vcap policers, so that one policer can be shared by multiple
> rules.
> >
> > Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@....com>
> > ---
> > +#define VSC9959_VCAP_POLICER_BASE	63
> > +#define VSC9959_VCAP_POLICER_MAX	383
> >
> 
> > +#define VSC7514_VCAP_POLICER_BASE			128
> > +#define VSC7514_VCAP_POLICER_MAX			191
> 
> I think this deserves an explanation.
> 
> The VSC7514 driver uses the max number of policers as 383 (0x17f) ever since
> commit b596229448dd ("net: mscc: ocelot: Add support for tcam"), aka the
> very beginning.
> 
> Yet, the documentation at "3.10.1 Policer Allocation"
> https://ww1.microchip.com/downloads/en/DeviceDoc/VMDS-10491.pdf
> says very clearly that there are only 192 policers indeed.
> 
> What's going on?

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?

> 
> 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.

Thanks,
Xiaoliang