linux-kernel - RE: [Enable Designware XGMAC VLAN Stripping Feature v2 1/1] net: stmmac: dwxgmac2: Add support for HW-accelerated VLAN Stripping

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Date: Tue, 28 May 2024 02:29:43 +0000
From: "Ng, Boon Khai" <boon.khai.ng@...el.com>
To: Andrew Lunn <andrew@...n.ch>
CC: Alexandre Torgue <alexandre.torgue@...s.st.com>, Jose Abreu
	<joabreu@...opsys.com>, "David S . Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-stm32@...md-mailman.stormreply.com"
	<linux-stm32@...md-mailman.stormreply.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Ang, Tien Sung" <tien.sung.ang@...el.com>,
	"G Thomas, Rohan" <rohan.g.thomas@...el.com>, "Looi, Hong Aun"
	<hong.aun.looi@...el.com>, Andy Shevchenko
	<andriy.shevchenko@...ux.intel.com>, Ilpo Jarvinen
	<ilpo.jarvinen@...ux.intel.com>
Subject: RE: [Enable Designware XGMAC VLAN Stripping Feature v2 1/1] net:
 stmmac: dwxgmac2: Add support for HW-accelerated VLAN Stripping

> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: Tuesday, May 28, 2024 3:00 AM
> To: Ng, Boon Khai <boon.khai.ng@...el.com>
> Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>; Jose Abreu
> <joabreu@...opsys.com>; David S . Miller <davem@...emloft.net>; Eric
> Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo
> Abeni <pabeni@...hat.com>; Maxime Coquelin
> <mcoquelin.stm32@...il.com>; netdev@...r.kernel.org; linux-stm32@st-
> md-mailman.stormreply.com; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...r.kernel.org; Ang, Tien Sung <tien.sung.ang@...el.com>; G
> Thomas, Rohan <rohan.g.thomas@...el.com>; Looi, Hong Aun
> <hong.aun.looi@...el.com>; Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com>; Ilpo Jarvinen
> <ilpo.jarvinen@...ux.intel.com>
> Subject: Re: [Enable Designware XGMAC VLAN Stripping Feature v2 1/1] net:
> stmmac: dwxgmac2: Add support for HW-accelerated VLAN Stripping
> 
> > This implementation was ported from the dwmac4 driver.
> 
> How does it differ from dwmac4? Can the dwmac4 implementation just be
> used, rather than duplicating all the code/bugs.

Hi Andrew, 5 years ago the driver was initially implemented separately, maybe need David S. Miller help to clarify this.
https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c

If you take a look at the code, the register mapping looks different at their TX MAC Configuration register and RX MAC Configuration register.
https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/stmicro/stmmac/dwmac4.h

So, for this XGMAC VLAN patch, the idea of getting the VLAN id from the descriptor is the same, but 
The register bit filed of getting the VLAN packet VALID is different. Thus, it need to be implemented separately. 

> 
> 	Andrew