linux-kernel - Re: [PATCH v3 4/5] net: hpe: Add GXP UMAC Driver

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Message-ID: <befbee5a-7b11-4948-a837-6311dd4d7276@lunn.ch>
Date:   Tue, 22 Aug 2023 22:00:52 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     "Hawkins, Nick" <nick.hawkins@....com>
Cc:     "christophe.jaillet@...adoo.fr" <christophe.jaillet@...adoo.fr>,
        "simon.horman@...igine.com" <simon.horman@...igine.com>,
        "Verdun, Jean-Marie" <verdun@....com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 4/5] net: hpe: Add GXP UMAC Driver

On Tue, Aug 22, 2023 at 07:00:49PM +0000, Hawkins, Nick wrote:
> 
> > <include/net/page_pool/helpers.h>
> 
> Hi Andrew,
> 
> I can't seem to find this file in linux master. Where is it?

~/linux$ ls include/net/page_pool/helpers.h
include/net/page_pool/helpers.h

When you say master, do you mean net-next/main? This is a network
driver, so you should be based on top of that tree.

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html#netdev-faq

> > Take a look at driver/net/ethernet/freescale/fec_main.c That
> > driver/device is of similar complexity to yours. It had a recent
> > change from its own buffer management to page pool. It
> > started with
> 
> I have looked over this driver and have a couple questions
> about the pages in general.
> 
> How do I determine what the correct pool size should be for the
> RX and TX?

There has been some recent discussion about that. Search the netdev
list over the last couple of week. 

> I must admit I am not familiar with XDP.
> Is it required for the page pool library?

Nope, not required at all. The FEC driver was first converted to page
pool, and then XDP support added. The conversion to page pool made the
driver faster, it could handle more packets per second. That is why i
suggested using it, plus it means less driver code, which means less
bugs.

	Andrew