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Message-ID: <e27edbff-8fa9-339a-4e6d-d72776286aa6@omp.ru>
Date: Thu, 25 Jan 2024 23:42:15 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Biju Das <biju.das.jz@...renesas.com>, "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 Yushchenko
<nikita.yoush@...entembedded.com>, <netdev@...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 <biju.das.au@...il.com>
Subject: Re: [PATCH net-next v2 1/2] ravb: Add Rx checksum offload support
On 1/24/24 1:21 PM, Biju Das wrote:
> TOE has hw support for calculating IP header and TCP/UDP/ICMP checksum
s/hw/hardware/.
> for both IPV4 and IPV6.
Those are usually called IPv4 and IPv6, no?
> Add Rx checksum offload supported by TOE for IPV4 and TCP/UDP protocols.
>
> For Rx, the result of checksum calculation is attached to last 4byte
> of ethernet frames.
"For Rx, the 4-byte result of checksum calculation is attached to the
Ethernet frames", you wanted to say?
> First 2bytes is result of IPV4 header checksum
> and next 2 bytes is TCP/UDP/ICMP.
TCP/UDP/ICMP checksum, you mean? Also, you alternatively say
TCP/UDP/ICMP and just TCP/UDP -- which one is correct?
> If frame does not have error "0000" attached to checksum calculation
"If a frame does not have checksum error, 0x0000 is attached as
a checksum calculation result", you wanted to say?
> result. For unsupported frames "ffff" is attached to checksum calculation
s/to/as/?
> result. Cases like IPV6, IPV4 header is always set to "FFFF".
"In case of an IPv6 packet, IPv4 checksum is always set to 0xFFFF",
you wanted to say?
> We can test this functionality by the below commands
>
> ethtool -K eth0 rx on --> to turn on Rx checksum offload
> ethtool -K eth0 rx off --> to turn off Rx 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 e0f8276cffed..a2c494a85d12 100644
> --- a/drivers/net/ethernet/renesas/ravb.h
> +++ b/drivers/net/ethernet/renesas/ravb.h
> @@ -44,6 +44,9 @@
> #define RAVB_RXTSTAMP_TYPE_ALL 0x00000006
> #define RAVB_RXTSTAMP_ENABLED 0x00000010 /* Enable RX timestamping */
>
> +/* GbEthernet TOE hardware checksum values */
> +#define TOE_RX_CSUM_OK 0x0000
As I said before, this is hardly needed...
[...]
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 0e3731f50fc2..59c7bedacef6 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -522,6 +522,26 @@ static int ravb_ring_init(struct net_device *ndev, int q)
> return -ENOMEM;
> }
>
> +static void ravb_csum_offload_init_gbeth(struct net_device *ndev)
I'd leave out _offload...
> +{
> + bool rx_enable = ndev->features & NETIF_F_RXCSUM;
> + u32 csr0;
> +
> + if (!rx_enable)
> + return;
> +
> + csr0 = ravb_read(ndev, CSR0);
Why read it here, if we'll write a constant to this reg at the end
of ravb_emac_init_gbeth()?
> + ravb_write(ndev, csr0 & ~(CSR0_RPE | CSR0_TPE), CSR0);
We can just write 0 here, no?
> + if (ravb_wait(ndev, CSR0, CSR0_RPE | CSR0_TPE, 0)) {
> + netdev_err(ndev, "Timeout Enabling HW CSUM failed\n");
"Timeout enabling hardware checksum\n", perhaps?
[...]
> +
> + ravb_write(ndev, csr0, CSR0);
I think we should move:
ravb_write(ndev, CSR0_TPE | CSR0_RPE, CSR0);
from ravb_emac_init_gbeth() here...
> +}
> +
[...]
> @@ -734,6 +755,32 @@ static void ravb_get_tx_tstamp(struct net_device *ndev)
> }
> }
>
> +static void ravb_rx_csum_gbeth(struct sk_buff *skb)
> +{
> + __wsum csum_ip_hdr, csum_proto;
> + u8 *hw_csum;
> +
> + /* The hardware checksum status is contained in sizeof(__sum16) * 2 = 4
> + * bytes appended to packet data. First 2 bytes is ip header csum and
> + * last 2 bytes is protocol csum.
> + */
> + if (unlikely(skb->len < sizeof(__sum16) * 2))
> + return;
> +
> + hw_csum = skb_tail_pointer(skb) - sizeof(__sum16);
> + csum_proto = csum_unfold((__force __sum16)get_unaligned_le16(hw_csum));
> +
> + hw_csum -= sizeof(__sum16);
> + csum_ip_hdr = csum_unfold((__force __sum16)get_unaligned_le16(hw_csum));
> + skb_trim(skb, skb->len - 2 * sizeof(__sum16));
> +
> + /* TODO: IPV6 Rx csum */
> + if (skb->protocol == htons(ETH_P_IP) && csum_ip_hdr == TOE_RX_CSUM_OK &&
> + csum_proto == TOE_RX_CSUM_OK)
> + /* Hardware validated our checksum */
> + skb->ip_summed = CHECKSUM_UNNECESSARY;
Don't we need to set skb->csum_level?
[...]
> @@ -2337,8 +2388,32 @@ static void ravb_set_rx_csum(struct net_device *ndev, bool enable)
> static int ravb_set_features_gbeth(struct net_device *ndev,
> netdev_features_t features)
> {
> - /* Place holder */
> - return 0;
> + netdev_features_t changed = ndev->features ^ features;
> + struct ravb_private *priv = netdev_priv(ndev);
> + unsigned long flags;
> + u32 csr0;
> + int ret;
> +
> + spin_lock_irqsave(&priv->lock, flags);
> + csr0 = ravb_read(ndev, CSR0);
> + ravb_write(ndev, csr0 & ~(CSR0_RPE | CSR0_TPE), CSR0);
> + ret = ravb_wait(ndev, CSR0, CSR0_RPE | CSR0_TPE, 0);
> + if (ret)
> + goto err_wait;
I don't understand: why do you clear the CSR0 bits even if
(changed & NETIF_F_RXCSUM) is 0? This looks very wrong...
> +
> + if (changed & NETIF_F_RXCSUM) {
> + if (features & NETIF_F_RXCSUM)
> + ravb_write(ndev, CSR2_ALL, CSR2);
> + else
> + ravb_write(ndev, 0, CSR2);
> + }
I think you should put that into a separate function, like
is done for the EhterAVB...
[...]
> @@ -2518,6 +2593,8 @@ static const struct ravb_hw_info gbeth_hw_info = {
> .emac_init = ravb_emac_init_gbeth,
> .gstrings_stats = ravb_gstrings_stats_gbeth,
> .gstrings_size = sizeof(ravb_gstrings_stats_gbeth),
> + .net_hw_features = NETIF_F_RXCSUM,
> + .net_features = NETIF_F_RXCSUM,
What about NETIF_F_IP_CSUM, BTW?
[...]
MBR, Sergey
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