[net PATCH v3 0/2] Fix maximum TX/RX frame sizes in ravb driver

[net PATCH v3 0/2] Fix maximum TX/RX frame sizes in ravb driver

[Paul Barker]

These patches fix a couple of bugs in the maximum supported TX/RX frame
sizes in the ravb driver.

  * For the GbEth IP, we were advertising a maximum TX frame size/MTU
    that was larger that the maximum the hardware can transmit.

  * For the R-Car AVB IP, we were unnecessarily setting the maximum RX
    frame size/MRU based on the MTU, which by default is smaller than
    the maximum the hardware can receive.

For the R-Car AVB IP, the maximum TX frame size should be 2047 (not
2048), but additional work will be required to validate that change so
it is not included in this series.

Changes v2->v3:
  * Pick up Reviewed-by tag and suggested comment improvement from
    Niklas.
Changes v1->v2:
  * Rebase on net tree as these are both bugfixes.
  * Pick up Reviewed-by tags.

Paul Barker (2):
  net: ravb: Fix maximum TX frame size for GbEth devices
  net: ravb: Fix R-Car RX frame size limit

 drivers/net/ethernet/renesas/ravb.h      |  1 +
 drivers/net/ethernet/renesas/ravb_main.c | 18 +++++++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

-- 
2.43.0

[net PATCH v3 1/2] net: ravb: Fix maximum TX frame size for GbEth devices

[Paul Barker]

The datasheets for all SoCs using the GbEth IP specify a maximum
transmission frame size of 1.5 kByte. I've confirmed through internal
discussions that support for 1522 byte frames has been validated, which
allows us to support the default MTU of 1500 bytes after reserving space
for the Ethernet header, frame checksums and an optional VLAN tag.

Fixes: 2e95e08ac009 ("ravb: Add rx_max_buf_size to struct ravb_hw_info")
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
---
 drivers/net/ethernet/renesas/ravb.h      | 1 +
 drivers/net/ethernet/renesas/ravb_main.c | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 9893c91af105..a7de5cf6b317 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -1052,6 +1052,7 @@ struct ravb_hw_info {
 	netdev_features_t net_features;
 	int stats_len;
 	u32 tccr_mask;
+	u32 tx_max_frame_size;
 	u32 rx_max_frame_size;
 	u32 rx_buffer_size;
 	u32 rx_desc_size;
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index c7ec23688d56..e73cdba58516 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2674,6 +2674,7 @@ static const struct ravb_hw_info ravb_gen2_hw_info = {
 	.net_features = NETIF_F_RXCSUM,
 	.stats_len = ARRAY_SIZE(ravb_gstrings_stats),
 	.tccr_mask = TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3,
+	.tx_max_frame_size = SZ_2K,
 	.rx_max_frame_size = SZ_2K,
 	.rx_buffer_size = SZ_2K +
 			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
@@ -2696,6 +2697,7 @@ static const struct ravb_hw_info ravb_gen3_hw_info = {
 	.net_features = NETIF_F_RXCSUM,
 	.stats_len = ARRAY_SIZE(ravb_gstrings_stats),
 	.tccr_mask = TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3,
+	.tx_max_frame_size = SZ_2K,
 	.rx_max_frame_size = SZ_2K,
 	.rx_buffer_size = SZ_2K +
 			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
@@ -2721,6 +2723,7 @@ static const struct ravb_hw_info ravb_gen4_hw_info = {
 	.net_features = NETIF_F_RXCSUM,
 	.stats_len = ARRAY_SIZE(ravb_gstrings_stats),
 	.tccr_mask = TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3,
+	.tx_max_frame_size = SZ_2K,
 	.rx_max_frame_size = SZ_2K,
 	.rx_buffer_size = SZ_2K +
 			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
@@ -2770,6 +2773,7 @@ static const struct ravb_hw_info gbeth_hw_info = {
 	.net_features = NETIF_F_RXCSUM | NETIF_F_HW_CSUM,
 	.stats_len = ARRAY_SIZE(ravb_gstrings_stats_gbeth),
 	.tccr_mask = TCCR_TSRQ0,
+	.tx_max_frame_size = 1522,
 	.rx_max_frame_size = SZ_8K,
 	.rx_buffer_size = SZ_2K,
 	.rx_desc_size = sizeof(struct ravb_rx_desc),
@@ -2981,7 +2985,7 @@ static int ravb_probe(struct platform_device *pdev)
 	priv->avb_link_active_low =
 		of_property_read_bool(np, "renesas,ether-link-active-low");
 
-	ndev->max_mtu = info->rx_max_frame_size -
+	ndev->max_mtu = info->tx_max_frame_size -
 		(ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
 	ndev->min_mtu = ETH_MIN_MTU;
 
-- 
2.43.0

[net PATCH v3 2/2] net: ravb: Fix R-Car RX frame size limit

[Paul Barker]

The RX frame size limit should not be based on the current MTU setting.
Instead it should be based on the hardware capabilities.

While we're here, improve the description of the receive frame length
setting as suggested by Niklas.

Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
---
 drivers/net/ethernet/renesas/ravb_main.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index e73cdba58516..d2a6518532f3 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -555,8 +555,16 @@ static void ravb_emac_init_gbeth(struct net_device *ndev)
 
 static void ravb_emac_init_rcar(struct net_device *ndev)
 {
-	/* Receive frame limit set register */
-	ravb_write(ndev, ndev->mtu + ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN, RFLR);
+	struct ravb_private *priv = netdev_priv(ndev);
+
+	/* Set receive frame length
+	 *
+	 * The length set here describes the frame from the destination address
+	 * up to and including the CRC data. However only the frame data,
+	 * excluding the CRC, are transferred to memory. To allow for the
+	 * largest frames add the CRC length to the maximum Rx descriptor size.
+	 */
+	ravb_write(ndev, priv->info->rx_max_frame_size + ETH_FCS_LEN, RFLR);
 
 	/* EMAC Mode: PAUSE prohibition; Duplex; RX Checksum; TX; RX */
 	ravb_write(ndev, ECMR_ZPF | ECMR_DM |
-- 
2.43.0

Re: [net PATCH v3 1/2] net: ravb: Fix maximum TX frame size for GbEth devices

[Simon Horman]

On Wed, Sep 18, 2024 at 09:18:38AM +0100, Paul Barker wrote:
> The datasheets for all SoCs using the GbEth IP specify a maximum
> transmission frame size of 1.5 kByte. I've confirmed through internal
> discussions that support for 1522 byte frames has been validated, which
> allows us to support the default MTU of 1500 bytes after reserving space
> for the Ethernet header, frame checksums and an optional VLAN tag.
> 
> Fixes: 2e95e08ac009 ("ravb: Add rx_max_buf_size to struct ravb_hw_info")
> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [net PATCH v3 2/2] net: ravb: Fix R-Car RX frame size limit

[Simon Horman]

On Wed, Sep 18, 2024 at 09:18:39AM +0100, Paul Barker wrote:
> The RX frame size limit should not be based on the current MTU setting.
> Instead it should be based on the hardware capabilities.
> 
> While we're here, improve the description of the receive frame length
> setting as suggested by Niklas.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [net PATCH v3 0/2] Fix maximum TX/RX frame sizes in ravb driver

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Wed, 18 Sep 2024 09:18:37 +0100 you wrote:
> These patches fix a couple of bugs in the maximum supported TX/RX frame
> sizes in the ravb driver.
> 
>   * For the GbEth IP, we were advertising a maximum TX frame size/MTU
>     that was larger that the maximum the hardware can transmit.
> 
>   * For the R-Car AVB IP, we were unnecessarily setting the maximum RX
>     frame size/MRU based on the MTU, which by default is smaller than
>     the maximum the hardware can receive.
> 
> [...]

Here is the summary with links:
  - [net,v3,1/2] net: ravb: Fix maximum TX frame size for GbEth devices
    https://git.kernel.org/netdev/net/c/1d63864299ca
  - [net,v3,2/2] net: ravb: Fix R-Car RX frame size limit
    https://git.kernel.org/netdev/net/c/ec8234717db8

You are awesome, thank you!
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