* [PATCH v3] net: spacemit: k1-emac: fix jumbo frame support
@ 2026-01-29 4:29 Tomas Hlavacek
2026-01-29 5:29 ` Vivian Wang
2026-01-30 1:47 ` Jakub Kicinski
0 siblings, 2 replies; 3+ messages in thread
From: Tomas Hlavacek @ 2026-01-29 4:29 UTC (permalink / raw)
To: netdev
Cc: linux-riscv, spacemit, davem, edumazet, kuba, pabeni, dlan,
wangruikang, Tomas Hlavacek, stable
The driver never programs the MAC frame size and jabber registers,
causing the hardware to reject frames larger than the default 1518
bytes even when larger DMA buffers are allocated.
Program MAC_MAXIMUM_FRAME_SIZE, MAC_TRANSMIT_JABBER_SIZE, and
MAC_RECEIVE_JABBER_SIZE based on the configured MTU. Also fix the
maximum buffer size from 4096 to 4095, since the descriptor buffer
size field is only 12 bits. Account for double VLAN tags in frame
size calculations.
Fixes: bfec6d7f2001 ("net: spacemit: Add K1 Ethernet MAC")
Cc: stable@vger.kernel.org
Signed-off-by: Tomas Hlavacek <tmshlvck@gmail.com>
---
v3:
- Set all three frame/jabber registers, fix 12-bit buffer size field
overflow, use actual frame size with VLAN headroom consistently.
v2: https://lore.kernel.org/netdev/20260126171449.83288-1-tmshlvck@gmail.com/
- Added Fixes tag and Cc stable.
v1: https://lore.kernel.org/netdev/20260126135919.77168-1-tmshlvck@gmail.com/
---
drivers/net/ethernet/spacemit/k1_emac.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/spacemit/k1_emac.c b/drivers/net/ethernet/spacemit/k1_emac.c
index 220eb5ce7583..cd6879d7434c 100644
--- a/drivers/net/ethernet/spacemit/k1_emac.c
+++ b/drivers/net/ethernet/spacemit/k1_emac.c
@@ -12,6 +12,7 @@
#include <linux/dma-mapping.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
+#include <linux/if_vlan.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
@@ -38,7 +39,7 @@
#define EMAC_DEFAULT_BUFSIZE 1536
#define EMAC_RX_BUF_2K 2048
-#define EMAC_RX_BUF_4K 4096
+#define EMAC_RX_BUF_MAX FIELD_MAX(RX_DESC_1_BUFFER_SIZE_1_MASK)
/* Tuning parameters from SpacemiT */
#define EMAC_TX_FRAMES 64
@@ -202,8 +203,7 @@ static void emac_init_hw(struct emac_priv *priv)
{
/* Destination address for 802.3x Ethernet flow control */
u8 fc_dest_addr[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x01 };
-
- u32 rxirq = 0, dma = 0;
+ u32 rxirq = 0, dma = 0, frame_sz;
regmap_set_bits(priv->regmap_apmu,
priv->regmap_apmu_offset + APMU_EMAC_CTRL_REG,
@@ -228,6 +228,15 @@ static void emac_init_hw(struct emac_priv *priv)
DEFAULT_TX_THRESHOLD);
emac_wr(priv, MAC_RECEIVE_PACKET_START_THRESHOLD, DEFAULT_RX_THRESHOLD);
+ /* Set maximum frame size and jabber size based on configured MTU,
+ * accounting for Ethernet header, double VLAN tags, and FCS.
+ */
+ frame_sz = priv->ndev->mtu + ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN;
+
+ emac_wr(priv, MAC_MAXIMUM_FRAME_SIZE, frame_sz);
+ emac_wr(priv, MAC_TRANSMIT_JABBER_SIZE, frame_sz);
+ emac_wr(priv, MAC_RECEIVE_JABBER_SIZE, frame_sz);
+
/* Configure flow control (enabled in emac_adjust_link() later) */
emac_set_mac_addr_reg(priv, fc_dest_addr, MAC_FC_SOURCE_ADDRESS_HIGH);
emac_wr(priv, MAC_FC_PAUSE_HIGH_THRESHOLD, DEFAULT_FC_FIFO_HIGH);
@@ -924,14 +933,14 @@ static int emac_change_mtu(struct net_device *ndev, int mtu)
return -EBUSY;
}
- frame_len = mtu + ETH_HLEN + ETH_FCS_LEN;
+ frame_len = mtu + ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN;
if (frame_len <= EMAC_DEFAULT_BUFSIZE)
priv->dma_buf_sz = EMAC_DEFAULT_BUFSIZE;
else if (frame_len <= EMAC_RX_BUF_2K)
priv->dma_buf_sz = EMAC_RX_BUF_2K;
else
- priv->dma_buf_sz = EMAC_RX_BUF_4K;
+ priv->dma_buf_sz = EMAC_RX_BUF_MAX;
ndev->mtu = mtu;
@@ -2005,7 +2014,7 @@ static int emac_probe(struct platform_device *pdev)
ndev->hw_features = NETIF_F_SG;
ndev->features |= ndev->hw_features;
- ndev->max_mtu = EMAC_RX_BUF_4K - (ETH_HLEN + ETH_FCS_LEN);
+ ndev->max_mtu = EMAC_RX_BUF_MAX - (ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN);
ndev->pcpu_stat_type = NETDEV_PCPU_STAT_DSTATS;
priv = netdev_priv(ndev);
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH v3] net: spacemit: k1-emac: fix jumbo frame support
2026-01-29 4:29 [PATCH v3] net: spacemit: k1-emac: fix jumbo frame support Tomas Hlavacek
@ 2026-01-29 5:29 ` Vivian Wang
2026-01-30 1:47 ` Jakub Kicinski
1 sibling, 0 replies; 3+ messages in thread
From: Vivian Wang @ 2026-01-29 5:29 UTC (permalink / raw)
To: Tomas Hlavacek, netdev
Cc: linux-riscv, spacemit, davem, edumazet, kuba, pabeni, dlan,
stable
On 1/29/26 12:29, Tomas Hlavacek wrote:
> The driver never programs the MAC frame size and jabber registers,
> causing the hardware to reject frames larger than the default 1518
> bytes even when larger DMA buffers are allocated.
>
> Program MAC_MAXIMUM_FRAME_SIZE, MAC_TRANSMIT_JABBER_SIZE, and
> MAC_RECEIVE_JABBER_SIZE based on the configured MTU. Also fix the
> maximum buffer size from 4096 to 4095, since the descriptor buffer
> size field is only 12 bits. Account for double VLAN tags in frame
> size calculations.
>
> Fixes: bfec6d7f2001 ("net: spacemit: Add K1 Ethernet MAC")
> Cc: stable@vger.kernel.org
> Signed-off-by: Tomas Hlavacek <tmshlvck@gmail.com>
> ---
> v3:
> - Set all three frame/jabber registers, fix 12-bit buffer size field
> overflow, use actual frame size with VLAN headroom consistently.
>
> v2: https://lore.kernel.org/netdev/20260126171449.83288-1-tmshlvck@gmail.com/
> - Added Fixes tag and Cc stable.
>
> v1: https://lore.kernel.org/netdev/20260126135919.77168-1-tmshlvck@gmail.com/
> ---
> drivers/net/ethernet/spacemit/k1_emac.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/spacemit/k1_emac.c b/drivers/net/ethernet/spacemit/k1_emac.c
> index 220eb5ce7583..cd6879d7434c 100644
> --- a/drivers/net/ethernet/spacemit/k1_emac.c
> +++ b/drivers/net/ethernet/spacemit/k1_emac.c
> @@ -12,6 +12,7 @@
> #include <linux/dma-mapping.h>
> #include <linux/etherdevice.h>
> #include <linux/ethtool.h>
> +#include <linux/if_vlan.h>
> #include <linux/interrupt.h>
> #include <linux/io.h>
> #include <linux/iopoll.h>
> @@ -38,7 +39,7 @@
>
> #define EMAC_DEFAULT_BUFSIZE 1536
> #define EMAC_RX_BUF_2K 2048
> -#define EMAC_RX_BUF_4K 4096
> +#define EMAC_RX_BUF_MAX FIELD_MAX(RX_DESC_1_BUFFER_SIZE_1_MASK)
>
> /* Tuning parameters from SpacemiT */
> #define EMAC_TX_FRAMES 64
> @@ -202,8 +203,7 @@ static void emac_init_hw(struct emac_priv *priv)
> {
> /* Destination address for 802.3x Ethernet flow control */
> u8 fc_dest_addr[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x01 };
> -
> - u32 rxirq = 0, dma = 0;
> + u32 rxirq = 0, dma = 0, frame_sz;
>
> regmap_set_bits(priv->regmap_apmu,
> priv->regmap_apmu_offset + APMU_EMAC_CTRL_REG,
> @@ -228,6 +228,15 @@ static void emac_init_hw(struct emac_priv *priv)
> DEFAULT_TX_THRESHOLD);
> emac_wr(priv, MAC_RECEIVE_PACKET_START_THRESHOLD, DEFAULT_RX_THRESHOLD);
>
> + /* Set maximum frame size and jabber size based on configured MTU,
> + * accounting for Ethernet header, double VLAN tags, and FCS.
> + */
> + frame_sz = priv->ndev->mtu + ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN;
> +
> + emac_wr(priv, MAC_MAXIMUM_FRAME_SIZE, frame_sz);
> + emac_wr(priv, MAC_TRANSMIT_JABBER_SIZE, frame_sz);
> + emac_wr(priv, MAC_RECEIVE_JABBER_SIZE, frame_sz);
> +
> /* Configure flow control (enabled in emac_adjust_link() later) */
> emac_set_mac_addr_reg(priv, fc_dest_addr, MAC_FC_SOURCE_ADDRESS_HIGH);
> emac_wr(priv, MAC_FC_PAUSE_HIGH_THRESHOLD, DEFAULT_FC_FIFO_HIGH);
> @@ -924,14 +933,14 @@ static int emac_change_mtu(struct net_device *ndev, int mtu)
> return -EBUSY;
> }
>
> - frame_len = mtu + ETH_HLEN + ETH_FCS_LEN;
> + frame_len = mtu + ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN;
>
> if (frame_len <= EMAC_DEFAULT_BUFSIZE)
> priv->dma_buf_sz = EMAC_DEFAULT_BUFSIZE;
> else if (frame_len <= EMAC_RX_BUF_2K)
> priv->dma_buf_sz = EMAC_RX_BUF_2K;
> else
> - priv->dma_buf_sz = EMAC_RX_BUF_4K;
> + priv->dma_buf_sz = EMAC_RX_BUF_MAX;
>
> ndev->mtu = mtu;
>
> @@ -2005,7 +2014,7 @@ static int emac_probe(struct platform_device *pdev)
> ndev->hw_features = NETIF_F_SG;
> ndev->features |= ndev->hw_features;
>
> - ndev->max_mtu = EMAC_RX_BUF_4K - (ETH_HLEN + ETH_FCS_LEN);
> + ndev->max_mtu = EMAC_RX_BUF_MAX - (ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN);
> ndev->pcpu_stat_type = NETDEV_PCPU_STAT_DSTATS;
>
> priv = netdev_priv(ndev);
Thanks for the fix. This essentially matches what I've been testing as well.
Reviewed-by: Vivian Wang <wangruikang@iscas.ac.cn>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v3] net: spacemit: k1-emac: fix jumbo frame support
2026-01-29 4:29 [PATCH v3] net: spacemit: k1-emac: fix jumbo frame support Tomas Hlavacek
2026-01-29 5:29 ` Vivian Wang
@ 2026-01-30 1:47 ` Jakub Kicinski
1 sibling, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2026-01-30 1:47 UTC (permalink / raw)
To: Tomas Hlavacek
Cc: netdev, linux-riscv, spacemit, davem, edumazet, pabeni, dlan,
wangruikang, stable
On Thu, 29 Jan 2026 05:29:08 +0100 Tomas Hlavacek wrote:
> Subject: [PATCH v3] net: spacemit: k1-emac: fix jumbo frame support
Could you repost this with subject:
[PATCH net v3] net: spacemit: k1-emac: fix jumbo frame support
The "net" after "PATCH" is crucial, since the patch conflicts with
net-next. I needs to be ingested specifically for net in the CI.
--
pw-bot: cr
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-01-30 1:47 ` Jakub Kicinski
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