-----Original Message-----
From: Florian Fainelli <f.fainelli@gmail.com>
Sent: Saturday, July 22, 2023 12:30 AM
To: Ng, Boon Khai <redacted>; Krzysztof Kozlowski
[off-list ref]; Boon@ecsmtp.png.intel.com;
Khai@ecsmtp.png.intel.com; Giuseppe Cavallaro [off-list ref];
Alexandre Torgue [off-list ref]; Jose Abreu
[off-list ref]; David S . Miller [off-list ref]; Eric
Dumazet [off-list ref]; Jakub Kicinski [off-list ref];
Paolo Abeni [off-list ref]; Maxime Coquelin
[off-list ref]; netdev@vger.kernel.org; linux-stm32@st-
md-mailman.stormreply.com; linux-arm-kernel@lists.infradead.org; linux-
kernel@vger.kernel.org
Cc: Shevchenko, Andriy <redacted>; Tham, Mun Yew
[off-list ref]; Swee, Leong Ching
[off-list ref]; G Thomas, Rohan
[off-list ref]; Shevchenko Andriy
[off-list ref]
Subject: Re: [Enable Designware XGMAC VLAN Stripping Feature 2/2] net:
stmmac: dwxgmac2: Add support for HW-accelerated VLAN Stripping



On 7/21/2023 9:12 AM, Ng, Boon Khai wrote:

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-----Original Message-----
From: Florian Fainelli <f.fainelli@gmail.com>
Sent: Friday, July 21, 2023 11:59 PM
To: Ng, Boon Khai <redacted>; Krzysztof Kozlowski
[off-list ref]; Boon@ecsmtp.png.intel.com;
Khai@ecsmtp.png.intel.com; Ng, Boon Khai [off-list ref];
Giuseppe Cavallaro [off-list ref]; Alexandre Torgue
[off-list ref]; Jose Abreu [off-list ref];
David S . Miller [off-list ref]; Eric Dumazet
[off-list ref]; Jakub Kicinski [off-list ref]; Paolo

Abeni

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[off-list ref]; Maxime Coquelin

[off-list ref];

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netdev@vger.kernel.org; linux-stm32@st-md- mailman.stormreply.com;
linux-arm-kernel@lists.infradead.org; linux- kernel@vger.kernel.org
Cc: Shevchenko, Andriy <redacted>; Tham, Mun

Yew

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[off-list ref]; Swee, Leong Ching
[off-list ref]; G Thomas, Rohan
[off-list ref]; Shevchenko Andriy
[off-list ref]
Subject: Re: [Enable Designware XGMAC VLAN Stripping Feature 2/2] net:
stmmac: dwxgmac2: Add support for HW-accelerated VLAN Stripping



On 7/21/2023 8:30 AM, Ng, Boon Khai wrote:

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-----Original Message-----
From: Krzysztof Kozlowski <krzk@kernel.org>
Sent: Friday, July 21, 2023 6:11 PM
To: Boon@ecsmtp.png.intel.com; Khai@ecsmtp.png.intel.com; "Ng
<boon.khai.ng"@intel.com; Giuseppe Cavallaro
[off-list ref]; Alexandre Torgue
[off-list ref]; Jose Abreu

[off-list ref];

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David S . Miller [off-list ref]; Eric Dumazet
[off-list ref]; Jakub Kicinski [off-list ref]; Paolo
Abeni [off-list ref]; Maxime Coquelin
[off-list ref]; netdev@vger.kernel.org;
linux-stm32@st- md-mailman.stormreply.com;
linux-arm-kernel@lists.infradead.org; linux- kernel@vger.kernel.org
Cc: Ng, Boon Khai <redacted>; Shevchenko, Andriy
[off-list ref]; Tham, Mun Yew
[off-list ref]; Swee, Leong Ching
[off-list ref]; G Thomas, Rohan
[off-list ref]; Shevchenko Andriy
[off-list ref]
Subject: Re: [Enable Designware XGMAC VLAN Stripping Feature 2/2]

net:

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stmmac: dwxgmac2: Add support for HW-accelerated VLAN Stripping

On 21/07/2023 08:26, Boon@ecsmtp.png.intel.com wrote:

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From: Boon Khai Ng <redacted>

Currently, VLAN tag stripping is done by software driver in
stmmac_rx_vlan(). This patch is to Add support for VLAN tag
stripping by the MAC hardware and MAC drivers to support it.
This is done by adding rx_hw_vlan() and set_hw_vlan_mode()
callbacks at stmmac_ops struct which are called from upper software

layer.

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...

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   	if (priv->dma_cap.vlhash) {
   		ndev->features |=

NETIF_F_HW_VLAN_CTAG_FILTER;

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   		ndev->features |=

NETIF_F_HW_VLAN_STAG_FILTER; diff --

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git

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a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 23d53ea04b24..bd7f3326a44c 100644

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -543,6 +543,12 @@ stmmac_probe_config_dt(struct

platform_device

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*pdev, u8 *mac)

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   			plat->flags |= STMMAC_FLAG_TSO_EN;
   	}

+	/* Rx VLAN HW Stripping */
+	if (of_property_read_bool(np, "snps,rx-vlan-offload")) {
+		dev_info(&pdev->dev, "RX VLAN HW Stripping\n");

Why? Drop.

This is an dts option export to dts for user to choose whether or
not they Want a Hardware stripping or a software stripping.

May I know what is the reason to drop this?

Because the networking stack already exposes knobs for drivers to
advertise and control VLAN stripping/insertion on RX/TX using ethtool
and feature bits (NETIF_F_HW_VLAN_CTAG_RX,

NETIF_F_HW_VLAN_CTAG_TX).

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Hi Florian,

Understood, but how does user choose to have the default option either
hardware strip or software strip, when the device just boot up?

You need the hardware to advertise it and decide as a maintainer of that
driver whether it makes sense to have one or the other behavior by default.

Okay got it.

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I don’t think ethool can "remember" the setting once the device get

rebooted?

If by "device" you mean a system that incorporates a XGMAC core, then I
suppose that is true, though you could have some user-space logic that does
remember the various ethtool options and re-applies them as soon as the
device is made available to user-space, this would not be too far fetched.

Okay, will try to search that, is adding the ethool command turning the
Hw vlan striping at the startup script consider one way of doing it?

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Any other suggestion of doing it other than using the dts method?

Let me ask you this question: what are you trying to solve by making this
configurable? HW stripping should always be more efficient, should not it, if
so, what would be the reasons for not enabling that by default? If not, then
leave it off and let users enable it if they feel like they want it.

Okay, so seem like it is solely depends on my side whether or not to turn it on by default,
Either way, if it go against the user will to have it on/off by default, they will need to write 
A startup script to turn the ethool on/off?

--
Florian