netdev - RE: [PATCH v4 net-next 2/2] ravb: Add Tx checksum offload support for GbEth

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Message-ID:
 <TYCPR01MB112697DC47B37005B92A8CAE486462@TYCPR01MB11269.jpnprd01.prod.outlook.com>
Date: Tue, 6 Feb 2024 17:47:20 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Sergey Shtylyov <s.shtylyov@....ru>, "David S. Miller"
	<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
CC: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>, Yoshihiro Shimoda
	<yoshihiro.shimoda.uh@...esas.com>, Wolfram Sang
	<wsa+renesas@...g-engineering.com>, nikita.yoush
	<nikita.yoush@...entembedded.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "linux-renesas-soc@...r.kernel.org"
	<linux-renesas-soc@...r.kernel.org>, Geert Uytterhoeven
	<geert+renesas@...der.be>, Prabhakar Mahadev Lad
	<prabhakar.mahadev-lad.rj@...renesas.com>, biju.das.au
	<biju.das.au@...il.com>
Subject: RE: [PATCH v4 net-next 2/2] ravb: Add Tx checksum offload support for
 GbEth

Hi Sergey,

> -----Original Message-----
> From: Sergey Shtylyov <s.shtylyov@....ru>
> Sent: Monday, February 5, 2024 8:27 PM
> Subject: Re: [PATCH v4 net-next 2/2] ravb: Add Tx checksum offload support
> for GbEth
> 
> On 2/3/24 5:25 PM, Biju Das wrote:
> 
> > TOE has hardware support for calculating IP header and TCP/UDP/ICMP
> > checksum for both IPv4 and IPv6.
> >
> > Add Tx checksum offload supported by TOE for IPv4 and TCP/UDP.
> >
> > For Tx, the result of checksum calculation is set to the checksum
> > field of each IPv4 Header/TCP/UDP/ICMP of ethernet frames. For the
> > unsupported frames, those fields are not changed. If a transmission
> > frame is an UDPv4 frame and its checksum value in the UDP header field
> > is 0x0000, TOE does not calculate checksum for UDP part of this frame
> > as it is optional function as per standards.
> >
> > We can test this functionality by the below commands
> >
> > ethtool -K eth0 tx on --> to turn on Tx checksum offload ethtool -K
> > eth0 tx off --> to turn off Tx checksum offload
> >
> > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> [...]
> 
> > diff --git a/drivers/net/ethernet/renesas/ravb.h
> > b/drivers/net/ethernet/renesas/ravb.h
> > index 64bf29d01ad0..d7b1c6d15a17 100644
> > --- a/drivers/net/ethernet/renesas/ravb.h
> > +++ b/drivers/net/ethernet/renesas/ravb.h
> [...]
> > @@ -981,6 +982,21 @@ enum CSR0_BIT {
> >  	CSR0_RPE	= 0x00000020,
> >  };
> >
> > +enum CSR1_BIT {
> > +	CSR1_TIP4	= 0x00000001,
> > +	CSR1_TTCP4	= 0x00000010,
> > +	CSR1_TUDP4	= 0x00000020,
> > +	CSR1_TICMP4	= 0x00000040,
> > +	CSR1_TTCP6	= 0x00100000,
> > +	CSR1_TUDP6	= 0x00200000,
> > +	CSR1_TICMP6	= 0x00400000,
> > +	CSR1_THOP	= 0x01000000,
> > +	CSR1_TROUT	= 0x02000000,
> > +	CSR1_TAHD	= 0x04000000,
> > +	CSR1_TDHD	= 0x08000000,
> > +	CSR1_ALL	= 0x0F700071,
> 
>    I doubt we really need CSR1_ALL...
OK, will drop it.

> 
> [...]
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c
> > b/drivers/net/ethernet/renesas/ravb_main.c
> > index 4f310bcee7c0..fee771f14fc5 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> [...]
> > @@ -524,16 +525,29 @@ static int ravb_ring_init(struct net_device
> > *ndev, int q)
> >
> >  static void ravb_csum_init_gbeth(struct net_device *ndev)  {
> > -	if (!(ndev->features & NETIF_F_RXCSUM))
> > +	bool tx_enable = ndev->features & NETIF_F_HW_CSUM;
> > +	bool rx_enable = ndev->features & NETIF_F_RXCSUM;
> > +
> > +	if (!(tx_enable || rx_enable))
> >  		goto done;
> >
> >  	ravb_write(ndev, 0, CSR0);
> > -	if (ravb_wait(ndev, CSR0, CSR0_RPE, 0)) {
> > +	if (ravb_wait(ndev, CSR0, CSR0_TPE | CSR0_RPE, 0)) {
> >  		netdev_err(ndev, "Timeout enabling hardware checksum\n");
> > -		ndev->features &= ~NETIF_F_RXCSUM;
> > +
> > +		if (tx_enable)
> > +			ndev->features &= ~NETIF_F_HW_CSUM;
> > +
> > +		if (rx_enable)
> > +			ndev->features &= ~NETIF_F_RXCSUM;
> >  	} else {
> > -		ravb_write(ndev, CSR2_ALL & ~(CSR2_RTCP6 | CSR2_RUDP6 |
> > -					      CSR2_RICMP6), CSR2);
> > +		if (tx_enable)
> > +			ravb_write(ndev, CSR1_ALL & ~(CSR1_TICMP4 | CSR1_TTCP6 |
> > +						      CSR1_TUDP6 | CSR1_TICMP6),
> CSR1);
> 
>    With the v6 bits 20...22 being 0, the bits 24...27 are ignored anyway,
> the manual says. So I think I'd prefer:
> 
> 			ravb_write(ndev, CSR1_TIP4 | CSR1_TTCP4 | CSR1_TUDP4,
> CSR1); [...]

OK.

> > @@ -2418,6 +2465,18 @@ static int ravb_set_features_gbeth(struct
> net_device *ndev,
> >  			goto done;
> >  	}
> >
> > +	if (changed & NETIF_F_HW_CSUM) {
> > +		if (features & NETIF_F_HW_CSUM)
> > +			val = CSR1_ALL & ~(CSR1_TICMP4 | CSR1_TTCP6 |
> > +					   CSR1_TUDP6 | CSR1_TICMP6);
> 
>    Likewise, I'd prefer:
> 
> 			val = CSR1_TIP4 | CSR1_TTCP4 | CS12_TUDP4;

OK, val = CSR1_TIP4 | CSR1_TTCP4 | CSR1_TUDP4;

Cheers,
Biju

> 
> [...]
> 
> MBR, Sergey