Add dmaengine framework to communicate with the xilinx DMAengine
driver(AXIDMA).
Axi ethernet driver uses separate channels for transmit and receive.
Add support for these channels to handle TX and RX with skb and
appropriate callbacks. Also add axi ethernet core interrupt for
dmaengine framework support.
The dmaengine framework was extended for metadata API support.
However it still needs further enhancements to make it well suited for
ethernet usecases. The ethernet features i.e ethtool set/get of DMA IP
properties, ndo_poll_controller,(mentioned in TODO) are not supported
and it requires follow-up discussions.
dmaengine support has a dependency on xilinx_dma as it uses
xilinx_vdma_channel_set_config() API to reset the DMA IP
which internally reset MAC prior to accessing MDIO.
Benchmark with netperf:
xilinx-zcu102-20232:~$ netperf -H 192.168.10.20 -t TCP_STREAM
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET
to 192.168.10.20 () port 0 AF_INET
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
131072 16384 16384 10.03 915.55
xilinx-zcu102-20232:~$ netperf -H 192.168.10.20 -t UDP_STREAM
MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET
to 192.168.10.20 () port 0 AF_INET
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec
212992 65507 10.00 18192 0 953.35
212992 10.00 18192 953.35
Signed-off-by: Radhey Shyam Pandey <[email protected]>
---
Changes for v7:
- Fix comment spaces.
- In xmit use correct XAE_FEATURE_PARTIAL_TX_CSUM define.
- Rename app to app_metadata.
- Switch to __netif_rx.
- In axienet_rx_submit_desc() add mapping error handling.
Changes for v6:
- Rename struct axi_skbuff to skbuf_dma_descriptor and removed
__packed attribute.
- Drop kmem_cache implementation and switch to using ring buffers.
- Remove __inline from axienet_init_dmaengine().
- Name labels after the target.
- Add error check for platform_get_irq_optional().
- Fix double space and no empty lines between call and its error check.
Changes for v5:
- Switch to amd.com email
- Modified commit description. Remove lore link, mention reset API,
add performance numbers.
- Fix kmem_cache resource leak on stop.
- Use dmaengine_terminate_sync instead of deprecated
dmaengine_terminate_all API.
Changes for v4:
- Remove the AXIENET_USE_DMA.
- Add dev_err_probe for dma_request_chan error handling.
- Add kmem_cache_destroy for create in axienet_setup_dma_chan.
- Add XILINX_DMA dependency in ethernet drier Kconfig file.
- move setup_dma_channel to init_dmaengine func
- Remove unlikely
if (unlikely(ret < 0))
- if (ret == 0) to if (!ret)
- Rename DMA_MEM_TO_DEV to DMA_TO_DEVICE
- Remove else check for lp->use_dmaengine = 1; in the probe.
Changes in V3:
- New patch for dmaengine framework support.
---
drivers/net/ethernet/xilinx/Kconfig | 1 +
drivers/net/ethernet/xilinx/xilinx_axienet.h | 33 ++
.../net/ethernet/xilinx/xilinx_axienet_main.c | 366 +++++++++++++++++-
3 files changed, 398 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/xilinx/Kconfig b/drivers/net/ethernet/xilinx/Kconfig
index 0014729b8865..35d96c633a33 100644
--- a/drivers/net/ethernet/xilinx/Kconfig
+++ b/drivers/net/ethernet/xilinx/Kconfig
@@ -26,6 +26,7 @@ config XILINX_EMACLITE
config XILINX_AXI_EMAC
tristate "Xilinx 10/100/1000 AXI Ethernet support"
depends on HAS_IOMEM
+ depends on XILINX_DMA
select PHYLINK
help
This driver supports the 10/100/1000 Ethernet from Xilinx for the
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 3ead0bac597b..807ead678551 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -14,6 +14,7 @@
#include <linux/interrupt.h>
#include <linux/if_vlan.h>
#include <linux/phylink.h>
+#include <linux/skbuff.h>
/* Packet size info */
#define XAE_HDR_SIZE 14 /* Size of Ethernet header */
@@ -378,6 +379,22 @@ struct axidma_bd {
#define XAE_NUM_MISC_CLOCKS 3
+/**
+ * struct skbuf_dma_descriptor - skb for each dma descriptor
+ * @sgl: Pointer for sglist.
+ * @desc: Pointer to dma descriptor.
+ * @dma_address: dma address of sglist.
+ * @skb: Pointer to SKB transferred using DMA
+ * @sg_len: number of entries in the sglist.
+ */
+struct skbuf_dma_descriptor {
+ struct scatterlist sgl[MAX_SKB_FRAGS + 1];
+ struct dma_async_tx_descriptor *desc;
+ dma_addr_t dma_address;
+ struct sk_buff *skb;
+ int sg_len;
+};
+
/**
* struct axienet_local - axienet private per device data
* @ndev: Pointer for net_device to which it will be attached.
@@ -436,6 +453,14 @@ struct axidma_bd {
* @coalesce_count_tx: Store the irq coalesce on TX side.
* @coalesce_usec_tx: IRQ coalesce delay for TX
* @use_dmaengine: flag to check dmaengine framework usage.
+ * @tx_chan: TX DMA channel.
+ * @rx_chan: RX DMA channel.
+ * @tx_skb_ring: Pointer to TX skb ring buffer array.
+ * @rx_skb_ring: Pointer to RX skb ring buffer array.
+ * @tx_ring_head: TX skb ring buffer head index.
+ * @tx_ring_tail: TX skb ring buffer tail index.
+ * @rx_ring_head: RX skb ring buffer head index.
+ * @rx_ring_tail: RX skb ring buffer tail index.
*/
struct axienet_local {
struct net_device *ndev;
@@ -501,6 +526,14 @@ struct axienet_local {
u32 coalesce_count_tx;
u32 coalesce_usec_tx;
u8 use_dmaengine;
+ struct dma_chan *tx_chan;
+ struct dma_chan *rx_chan;
+ struct skbuf_dma_descriptor **tx_skb_ring;
+ struct skbuf_dma_descriptor **rx_skb_ring;
+ int tx_ring_head;
+ int tx_ring_tail;
+ int rx_ring_head;
+ int rx_ring_tail;
};
/**
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 67901700e296..3b522dc2f979 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -38,6 +38,10 @@
#include <linux/phy.h>
#include <linux/mii.h>
#include <linux/ethtool.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma/xilinx_dma.h>
+#include <linux/circ_buf.h>
#include "xilinx_axienet.h"
@@ -47,6 +51,9 @@
#define TX_BD_NUM_MIN (MAX_SKB_FRAGS + 1)
#define TX_BD_NUM_MAX 4096
#define RX_BD_NUM_MAX 4096
+#define DMA_NUM_APP_WORDS 5
+#define LEN_APP 4
+#define RX_BUF_NUM_DEFAULT 128
/* Must be shorter than length of ethtool_drvinfo.driver field to fit */
#define DRIVER_NAME "xaxienet"
@@ -55,6 +62,8 @@
#define AXIENET_REGS_N 40
+static int axienet_rx_submit_desc(struct net_device *ndev);
+
/* Match table for of_platform binding */
static const struct of_device_id axienet_of_match[] = {
{ .compatible = "xlnx,axi-ethernet-1.00.a", },
@@ -120,6 +129,16 @@ static struct axienet_option axienet_options[] = {
{}
};
+static struct skbuf_dma_descriptor *axienet_get_rx_desc(struct axienet_local *lp, int i)
+{
+ return lp->rx_skb_ring[i & (RX_BUF_NUM_DEFAULT - 1)];
+}
+
+static struct skbuf_dma_descriptor *axienet_get_tx_desc(struct axienet_local *lp, int i)
+{
+ return lp->tx_skb_ring[i & (TX_BD_NUM_MAX - 1)];
+}
+
/**
* axienet_dma_in32 - Memory mapped Axi DMA register read
* @lp: Pointer to axienet local structure
@@ -727,6 +746,112 @@ static inline int axienet_check_tx_bd_space(struct axienet_local *lp,
return 0;
}
+/**
+ * axienet_dma_tx_cb - DMA engine callback for TX channel.
+ * @data: Pointer to the axienet_local structure.
+ * @result: error reporting through dmaengine_result.
+ * This function is called by dmaengine driver for TX channel to notify
+ * that the transmit is done.
+ */
+static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result)
+{
+ struct axienet_local *lp = data;
+ struct skbuf_dma_descriptor *skbuf_dma;
+
+ skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_tail++);
+ u64_stats_update_begin(&lp->tx_stat_sync);
+ u64_stats_add(&lp->tx_bytes, skbuf_dma->skb->len);
+ u64_stats_add(&lp->tx_packets, 1);
+ u64_stats_update_end(&lp->tx_stat_sync);
+ dma_unmap_sg(lp->dev, skbuf_dma->sgl, skbuf_dma->sg_len, DMA_TO_DEVICE);
+ dev_kfree_skb_any(skbuf_dma->skb);
+}
+
+/**
+ * axienet_start_xmit_dmaengine - Starts the transmission.
+ * @skb: sk_buff pointer that contains data to be Txed.
+ * @ndev: Pointer to net_device structure.
+ *
+ * Return: NETDEV_TX_OK on success or any non space errors.
+ * NETDEV_TX_BUSY when free element in TX skb ring buffer
+ * is not available.
+ *
+ * This function is invoked from xmit to initiate transmission. The
+ * function sets the skbs, register dma call back API and submit
+ * the dma transaction.
+ * Additionally if checksum offloading is supported,
+ * it populates AXI Stream Control fields with appropriate values.
+ */
+static netdev_tx_t
+axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
+{
+ struct dma_async_tx_descriptor *dma_tx_desc = NULL;
+ struct axienet_local *lp = netdev_priv(ndev);
+ struct skbuf_dma_descriptor *skbuf_dma;
+ u32 app_metadata[DMA_NUM_APP_WORDS] = {0};
+ u32 csum_start_off;
+ u32 csum_index_off;
+ int sg_len;
+ int ret;
+
+ sg_len = skb_shinfo(skb)->nr_frags + 1;
+ if (!CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX)) {
+ netif_stop_queue(ndev);
+ if (net_ratelimit())
+ netdev_warn(ndev, "TX ring unexpectedly full\n");
+ return NETDEV_TX_BUSY;
+ }
+
+ skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_head);
+ if (!skbuf_dma)
+ return NETDEV_TX_OK;
+
+ lp->tx_ring_head++;
+ sg_init_table(skbuf_dma->sgl, sg_len);
+ ret = skb_to_sgvec(skb, skbuf_dma->sgl, 0, skb->len);
+ if (ret < 0)
+ return NETDEV_TX_OK;
+
+ ret = dma_map_sg(lp->dev, skbuf_dma->sgl, sg_len, DMA_TO_DEVICE);
+ if (!ret)
+ return NETDEV_TX_OK;
+
+ /* Fill up app fields for checksum */
+ if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ if (lp->features & XAE_FEATURE_FULL_TX_CSUM) {
+ /* Tx Full Checksum Offload Enabled */
+ app_metadata[0] |= 2;
+ } else if (lp->features & XAE_FEATURE_PARTIAL_TX_CSUM) {
+ csum_start_off = skb_transport_offset(skb);
+ csum_index_off = csum_start_off + skb->csum_offset;
+ /* Tx Partial Checksum Offload Enabled */
+ app_metadata[0] |= 1;
+ app_metadata[1] = (csum_start_off << 16) | csum_index_off;
+ }
+ } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+ app_metadata[0] |= 2; /* Tx Full Checksum Offload Enabled */
+ }
+
+ dma_tx_desc = lp->tx_chan->device->device_prep_slave_sg(lp->tx_chan, skbuf_dma->sgl,
+ sg_len, DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT, (void *)app_metadata);
+ if (!dma_tx_desc)
+ goto xmit_error_unmap_sg;
+
+ skbuf_dma->skb = skb;
+ skbuf_dma->sg_len = sg_len;
+ dma_tx_desc->callback_param = lp;
+ dma_tx_desc->callback_result = axienet_dma_tx_cb;
+ dmaengine_submit(dma_tx_desc);
+ dma_async_issue_pending(lp->tx_chan);
+
+ return NETDEV_TX_OK;
+
+xmit_error_unmap_sg:
+ dma_unmap_sg(lp->dev, skbuf_dma->sgl, sg_len, DMA_TO_DEVICE);
+ return NETDEV_TX_OK;
+}
+
/**
* axienet_tx_poll - Invoked once a transmit is completed by the
* Axi DMA Tx channel.
@@ -911,7 +1036,43 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
if (!lp->use_dmaengine)
return axienet_start_xmit_legacy(skb, ndev);
else
- return NETDEV_TX_BUSY;
+ return axienet_start_xmit_dmaengine(skb, ndev);
+}
+
+/**
+ * axienet_dma_rx_cb - DMA engine callback for RX channel.
+ * @data: Pointer to the skbuf_dma_descriptor structure.
+ * @result: error reporting through dmaengine_result.
+ * This function is called by dmaengine driver for RX channel to notify
+ * that the packet is received.
+ */
+static void axienet_dma_rx_cb(void *data, const struct dmaengine_result *result)
+{
+ struct axienet_local *lp = data;
+ struct skbuf_dma_descriptor *skbuf_dma;
+ size_t meta_len, meta_max_len, rx_len;
+ struct sk_buff *skb;
+ u32 *app_metadata;
+
+ skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_tail++);
+ skb = skbuf_dma->skb;
+ app_metadata = dmaengine_desc_get_metadata_ptr(skbuf_dma->desc, &meta_len,
+ &meta_max_len);
+ dma_unmap_single(lp->dev, skbuf_dma->dma_address, lp->max_frm_size,
+ DMA_FROM_DEVICE);
+ /* TODO: Derive app word index programmatically */
+ rx_len = (app_metadata[LEN_APP] & 0xFFFF);
+ skb_put(skb, rx_len);
+ skb->protocol = eth_type_trans(skb, lp->ndev);
+ skb->ip_summed = CHECKSUM_NONE;
+
+ __netif_rx(skb);
+ u64_stats_update_begin(&lp->rx_stat_sync);
+ u64_stats_add(&lp->rx_packets, 1);
+ u64_stats_add(&lp->rx_bytes, rx_len);
+ u64_stats_update_end(&lp->rx_stat_sync);
+ axienet_rx_submit_desc(lp->ndev);
+ dma_async_issue_pending(lp->rx_chan);
}
/**
@@ -1147,6 +1308,147 @@ static irqreturn_t axienet_eth_irq(int irq, void *_ndev)
static void axienet_dma_err_handler(struct work_struct *work);
+/**
+ * axienet_rx_submit_desc - Submit the descriptors with required data
+ * like call backup API, skb buffer.. etc to dmaengine.
+ *
+ * @ndev: net_device pointer
+ *
+ *Return: 0, on success.
+ * non-zero error value on failure
+ */
+static int axienet_rx_submit_desc(struct net_device *ndev)
+{
+ struct dma_async_tx_descriptor *dma_rx_desc = NULL;
+ struct axienet_local *lp = netdev_priv(ndev);
+ struct skbuf_dma_descriptor *skbuf_dma;
+ struct sk_buff *skb;
+ dma_addr_t addr;
+ int ret;
+
+ skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_head);
+ if (!skbuf_dma)
+ return -ENOMEM;
+ lp->rx_ring_head++;
+ skb = netdev_alloc_skb(ndev, lp->max_frm_size);
+ if (!skb)
+ return -ENOMEM;
+
+ sg_init_table(skbuf_dma->sgl, 1);
+ addr = dma_map_single(lp->dev, skb->data, lp->max_frm_size, DMA_FROM_DEVICE);
+ if (unlikely(dma_mapping_error(lp->dev, addr))) {
+ netdev_err(ndev, "DMA mapping error\n");
+ ret = -ENOMEM;
+ goto rx_submit_err_free_skb;
+ }
+ sg_dma_address(skbuf_dma->sgl) = addr;
+ sg_dma_len(skbuf_dma->sgl) = lp->max_frm_size;
+ dma_rx_desc = dmaengine_prep_slave_sg(lp->rx_chan, skbuf_dma->sgl,
+ 1, DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT);
+ if (!dma_rx_desc) {
+ ret = -EINVAL;
+ goto rx_submit_err_free_skb;
+ }
+
+ skbuf_dma->skb = skb;
+ skbuf_dma->dma_address = sg_dma_address(skbuf_dma->sgl);
+ skbuf_dma->desc = dma_rx_desc;
+ dma_rx_desc->callback_param = lp;
+ dma_rx_desc->callback_result = axienet_dma_rx_cb;
+ dmaengine_submit(dma_rx_desc);
+
+ return 0;
+
+rx_submit_err_free_skb:
+ dma_unmap_single(lp->dev, addr, lp->max_frm_size, DMA_FROM_DEVICE);
+ dev_kfree_skb(skb);
+ return ret;
+}
+
+/**
+ * axienet_init_dmaengine - init the dmaengine code.
+ * @ndev: Pointer to net_device structure
+ *
+ * Return: 0, on success.
+ * non-zero error value on failure
+ *
+ * This is the dmaengine initialization code.
+ */
+static int axienet_init_dmaengine(struct net_device *ndev)
+{
+ struct axienet_local *lp = netdev_priv(ndev);
+ struct skbuf_dma_descriptor *skbuf_dma;
+ int i, ret;
+
+ lp->tx_chan = dma_request_chan(lp->dev, "tx_chan0");
+ if (IS_ERR(lp->tx_chan)) {
+ ret = PTR_ERR(lp->tx_chan);
+ return dev_err_probe(lp->dev, ret, "No Ethernet DMA (TX) channel found\n");
+ }
+
+ lp->rx_chan = dma_request_chan(lp->dev, "rx_chan0");
+ if (IS_ERR(lp->rx_chan)) {
+ ret = PTR_ERR(lp->rx_chan);
+ dev_err_probe(lp->dev, ret, "No Ethernet DMA (RX) channel found\n");
+ goto err_dma_release_tx;
+ }
+
+ lp->tx_ring_tail = 0;
+ lp->tx_ring_head = 0;
+ lp->rx_ring_tail = 0;
+ lp->rx_ring_head = 0;
+ lp->tx_skb_ring = kcalloc(TX_BD_NUM_MAX, sizeof(*lp->tx_skb_ring),
+ GFP_KERNEL);
+ if (!lp->tx_skb_ring) {
+ ret = -ENOMEM;
+ goto err_dma_release_rx;
+ }
+ for (i = 0; i < TX_BD_NUM_MAX; i++) {
+ skbuf_dma = kzalloc(sizeof(*skbuf_dma), GFP_KERNEL);
+ if (!skbuf_dma) {
+ ret = -ENOMEM;
+ goto err_free_tx_skb_ring;
+ }
+ lp->tx_skb_ring[i] = skbuf_dma;
+ }
+
+ lp->rx_skb_ring = kcalloc(RX_BUF_NUM_DEFAULT, sizeof(*lp->rx_skb_ring),
+ GFP_KERNEL);
+ if (!lp->rx_skb_ring) {
+ ret = -ENOMEM;
+ goto err_free_tx_skb_ring;
+ }
+ for (i = 0; i < RX_BUF_NUM_DEFAULT; i++) {
+ skbuf_dma = kzalloc(sizeof(*skbuf_dma), GFP_KERNEL);
+ if (!skbuf_dma) {
+ ret = -ENOMEM;
+ goto err_free_rx_skb_ring;
+ }
+ lp->rx_skb_ring[i] = skbuf_dma;
+ }
+ /* TODO: Instead of BD_NUM_DEFAULT use runtime support */
+ for (i = 0; i < RX_BUF_NUM_DEFAULT; i++)
+ axienet_rx_submit_desc(ndev);
+ dma_async_issue_pending(lp->rx_chan);
+
+ return 0;
+
+err_free_rx_skb_ring:
+ for (i = 0; i < RX_BUF_NUM_DEFAULT; i++)
+ kfree(lp->rx_skb_ring[i]);
+ kfree(lp->rx_skb_ring);
+err_free_tx_skb_ring:
+ for (i = 0; i < TX_BD_NUM_MAX; i++)
+ kfree(lp->tx_skb_ring[i]);
+ kfree(lp->tx_skb_ring);
+err_dma_release_rx:
+ dma_release_channel(lp->rx_chan);
+err_dma_release_tx:
+ dma_release_channel(lp->tx_chan);
+ return ret;
+}
+
/**
* axienet_init_legacy_dma - init the dma legacy code.
* @ndev: Pointer to net_device structure
@@ -1238,7 +1540,24 @@ static int axienet_open(struct net_device *ndev)
phylink_start(lp->phylink);
- if (!lp->use_dmaengine) {
+ if (lp->use_dmaengine) {
+ /* Enable interrupts for Axi Ethernet core (if defined) */
+ if (lp->eth_irq > 0) {
+ ret = request_irq(lp->eth_irq, axienet_eth_irq, IRQF_SHARED,
+ ndev->name, ndev);
+ if (ret)
+ goto error_code;
+ }
+
+ ret = axienet_init_dmaengine(ndev);
+
+ if (ret < 0) {
+ if (lp->eth_irq > 0)
+ free_irq(lp->eth_irq, ndev);
+ goto error_code;
+ }
+
+ } else {
ret = axienet_init_legacy_dma(ndev);
if (ret)
goto error_code;
@@ -1266,6 +1585,7 @@ static int axienet_open(struct net_device *ndev)
static int axienet_stop(struct net_device *ndev)
{
struct axienet_local *lp = netdev_priv(ndev);
+ int i;
dev_dbg(&ndev->dev, "axienet_close()\n");
@@ -1286,6 +1606,21 @@ static int axienet_stop(struct net_device *ndev)
free_irq(lp->tx_irq, ndev);
free_irq(lp->rx_irq, ndev);
axienet_dma_bd_release(ndev);
+ } else {
+ dmaengine_terminate_sync(lp->tx_chan);
+ dmaengine_synchronize(lp->tx_chan);
+ dmaengine_terminate_sync(lp->rx_chan);
+ dmaengine_synchronize(lp->rx_chan);
+
+ for (i = 0; i < TX_BD_NUM_MAX; i++)
+ kfree(lp->tx_skb_ring[i]);
+ kfree(lp->tx_skb_ring);
+ for (i = 0; i < RX_BUF_NUM_DEFAULT; i++)
+ kfree(lp->rx_skb_ring[i]);
+ kfree(lp->rx_skb_ring);
+
+ dma_release_channel(lp->rx_chan);
+ dma_release_channel(lp->tx_chan);
}
axienet_iow(lp, XAE_IE_OFFSET, 0);
@@ -2141,6 +2476,33 @@ static int axienet_probe(struct platform_device *pdev)
}
netif_napi_add(ndev, &lp->napi_rx, axienet_rx_poll);
netif_napi_add(ndev, &lp->napi_tx, axienet_tx_poll);
+ } else {
+ struct xilinx_vdma_config cfg;
+ struct dma_chan *tx_chan;
+
+ lp->eth_irq = platform_get_irq_optional(pdev, 0);
+ if (lp->eth_irq < 0 && lp->eth_irq != -ENXIO) {
+ ret = lp->eth_irq;
+ goto cleanup_clk;
+ }
+ tx_chan = dma_request_chan(lp->dev, "tx_chan0");
+ if (IS_ERR(tx_chan)) {
+ ret = PTR_ERR(tx_chan);
+ dev_err_probe(lp->dev, ret, "No Ethernet DMA (TX) channel found\n");
+ goto cleanup_clk;
+ }
+
+ cfg.reset = 1;
+ /* As name says VDMA but it has support for DMA channel reset */
+ ret = xilinx_vdma_channel_set_config(tx_chan, &cfg);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Reset channel failed\n");
+ dma_release_channel(tx_chan);
+ goto cleanup_clk;
+ }
+
+ dma_release_channel(tx_chan);
+ lp->use_dmaengine = 1;
}
/* Check for Ethernet core IRQ (optional) */
--
2.34.1
On Thu, 28 Sep 2023 01:02:31 +0530 Radhey Shyam Pandey wrote:
> +static int axienet_rx_submit_desc(struct net_device *ndev);
can the forward declaration be avoided?
> +/**
> + * axienet_dma_tx_cb - DMA engine callback for TX channel.
> + * @data: Pointer to the axienet_local structure.
> + * @result: error reporting through dmaengine_result.
> + * This function is called by dmaengine driver for TX channel to notify
> + * that the transmit is done.
> + */
> +static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result)
> +{
> + struct axienet_local *lp = data;
> + struct skbuf_dma_descriptor *skbuf_dma;
> +
> + skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_tail++);
> + u64_stats_update_begin(&lp->tx_stat_sync);
> + u64_stats_add(&lp->tx_bytes, skbuf_dma->skb->len);
> + u64_stats_add(&lp->tx_packets, 1);
> + u64_stats_update_end(&lp->tx_stat_sync);
> + dma_unmap_sg(lp->dev, skbuf_dma->sgl, skbuf_dma->sg_len, DMA_TO_DEVICE);
> + dev_kfree_skb_any(skbuf_dma->skb);
dev_consume_skb_any(), kfree is for drops
> +/**
> + * axienet_start_xmit_dmaengine - Starts the transmission.
> + * @skb: sk_buff pointer that contains data to be Txed.
> + * @ndev: Pointer to net_device structure.
> + *
> + * Return: NETDEV_TX_OK on success or any non space errors.
> + * NETDEV_TX_BUSY when free element in TX skb ring buffer
> + * is not available.
> + *
> + * This function is invoked from xmit to initiate transmission. The
> + * function sets the skbs, register dma call back API and submit
> + * the dma transaction.
> + * Additionally if checksum offloading is supported,
> + * it populates AXI Stream Control fields with appropriate values.
> + */
> +static netdev_tx_t
> +axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
> +{
> + struct dma_async_tx_descriptor *dma_tx_desc = NULL;
> + struct axienet_local *lp = netdev_priv(ndev);
> + struct skbuf_dma_descriptor *skbuf_dma;
> + u32 app_metadata[DMA_NUM_APP_WORDS] = {0};
> + u32 csum_start_off;
> + u32 csum_index_off;
> + int sg_len;
> + int ret;
> +
> + sg_len = skb_shinfo(skb)->nr_frags + 1;
> + if (!CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX)) {
> + netif_stop_queue(ndev);
> + if (net_ratelimit())
> + netdev_warn(ndev, "TX ring unexpectedly full\n");
I don't see you stopping the queue when the ring gets full,
am I not looking into the right place? Otherwise this is
sort of expected to occasionally hapen
> + return NETDEV_TX_BUSY;
> + }
> +
> + skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_head);
> + if (!skbuf_dma)
> + return NETDEV_TX_OK;
Leaks the skb?
> + lp->tx_ring_head++;
> + sg_init_table(skbuf_dma->sgl, sg_len);
> + ret = skb_to_sgvec(skb, skbuf_dma->sgl, 0, skb->len);
> + if (ret < 0)
> + return NETDEV_TX_OK;
> +
> + ret = dma_map_sg(lp->dev, skbuf_dma->sgl, sg_len, DMA_TO_DEVICE);
> + if (!ret)
> + return NETDEV_TX_OK;
> +
> + /* Fill up app fields for checksum */
> + if (skb->ip_summed == CHECKSUM_PARTIAL) {
> + if (lp->features & XAE_FEATURE_FULL_TX_CSUM) {
> + /* Tx Full Checksum Offload Enabled */
> + app_metadata[0] |= 2;
> + } else if (lp->features & XAE_FEATURE_PARTIAL_TX_CSUM) {
> + csum_start_off = skb_transport_offset(skb);
> + csum_index_off = csum_start_off + skb->csum_offset;
> + /* Tx Partial Checksum Offload Enabled */
> + app_metadata[0] |= 1;
> + app_metadata[1] = (csum_start_off << 16) | csum_index_off;
> + }
> + } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
> + app_metadata[0] |= 2; /* Tx Full Checksum Offload Enabled */
> + }
> +
> + dma_tx_desc = lp->tx_chan->device->device_prep_slave_sg(lp->tx_chan, skbuf_dma->sgl,
Possibly store the device_prep_slave_sg pointer to a temporary variable
to make this line less painfully long?
> + skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_head);
> + if (!skbuf_dma)
> + return -ENOMEM;
> + lp->rx_ring_head++;
> + skb = netdev_alloc_skb(ndev, lp->max_frm_size);
> + if (!skb)
> + return -ENOMEM;
> +
> + sg_init_table(skbuf_dma->sgl, 1);
> + addr = dma_map_single(lp->dev, skb->data, lp->max_frm_size, DMA_FROM_DEVICE);
> + if (unlikely(dma_mapping_error(lp->dev, addr))) {
> + netdev_err(ndev, "DMA mapping error\n");
needs rate limiting
> + ret = -ENOMEM;
> + goto rx_submit_err_free_skb;
is it legal to unmap dma error ?
> + }
> + sg_dma_address(skbuf_dma->sgl) = addr;
> + sg_dma_len(skbuf_dma->sgl) = lp->max_frm_size;
> + dma_rx_desc = dmaengine_prep_slave_sg(lp->rx_chan, skbuf_dma->sgl,
> + 1, DMA_DEV_TO_MEM,
> + DMA_PREP_INTERRUPT);
> +/**
> + * axienet_init_dmaengine - init the dmaengine code.
> + * @ndev: Pointer to net_device structure
> + *
> + * Return: 0, on success.
> + * non-zero error value on failure
> + *
> + * This is the dmaengine initialization code.
> + */
> +static int axienet_init_dmaengine(struct net_device *ndev)
> +{
> + struct axienet_local *lp = netdev_priv(ndev);
> + struct skbuf_dma_descriptor *skbuf_dma;
> + int i, ret;
> +
> + lp->tx_chan = dma_request_chan(lp->dev, "tx_chan0");
> + if (IS_ERR(lp->tx_chan)) {
> + ret = PTR_ERR(lp->tx_chan);
> + return dev_err_probe(lp->dev, ret, "No Ethernet DMA (TX) channel found\n");
Why use dev_err_probe()? This is not on the probe path. If ndo_open
fails it fails, it won't get retried later by itself, right?
> @@ -1238,7 +1540,24 @@ static int axienet_open(struct net_device *ndev)
>
> phylink_start(lp->phylink);
>
> - if (!lp->use_dmaengine) {
> + if (lp->use_dmaengine) {
> + /* Enable interrupts for Axi Ethernet core (if defined) */
> + if (lp->eth_irq > 0) {
> + ret = request_irq(lp->eth_irq, axienet_eth_irq, IRQF_SHARED,
> + ndev->name, ndev);
> + if (ret)
> + goto error_code;
> + }
> +
> + ret = axienet_init_dmaengine(ndev);
> +
pointless new line
> + if (ret < 0) {
> + if (lp->eth_irq > 0)
> + free_irq(lp->eth_irq, ndev);
can't this be on the error path?
> + goto error_code;
> + }
> +
pointless new line
> + } else {
--
pw-bot: cr
> -----Original Message-----
> From: Jakub Kicinski <[email protected]>
> Sent: Thursday, October 5, 2023 2:23 AM
> To: Pandey, Radhey Shyam <[email protected]>
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; Simek, Michal <[email protected]>;
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; linux-arm-
> [email protected]; git (AMD-Xilinx) <[email protected]>
> Subject: Re: [PATCH net-next v7 3/3] net: axienet: Introduce dmaengine
> support
>
> On Thu, 28 Sep 2023 01:02:31 +0530 Radhey Shyam Pandey wrote:
> > +static int axienet_rx_submit_desc(struct net_device *ndev);
>
> can the forward declaration be avoided?
axienet_dma_rx_cb()- make call to axienet_rx_submit_desc(). and
axienet_rx_submit_desc() registers axienet_dma_rx_cb as callback
func. There seems to be circular dependency.
>
> > +/**
> > + * axienet_dma_tx_cb - DMA engine callback for TX channel.
> > + * @data: Pointer to the axienet_local structure.
> > + * @result: error reporting through dmaengine_result.
> > + * This function is called by dmaengine driver for TX channel to
> > +notify
> > + * that the transmit is done.
> > + */
> > +static void axienet_dma_tx_cb(void *data, const struct
> > +dmaengine_result *result) {
> > + struct axienet_local *lp = data;
> > + struct skbuf_dma_descriptor *skbuf_dma;
> > +
> > + skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_tail++);
> > + u64_stats_update_begin(&lp->tx_stat_sync);
> > + u64_stats_add(&lp->tx_bytes, skbuf_dma->skb->len);
> > + u64_stats_add(&lp->tx_packets, 1);
> > + u64_stats_update_end(&lp->tx_stat_sync);
> > + dma_unmap_sg(lp->dev, skbuf_dma->sgl, skbuf_dma->sg_len,
> DMA_TO_DEVICE);
> > + dev_kfree_skb_any(skbuf_dma->skb);
>
> dev_consume_skb_any(), kfree is for drops
Thanks, will use dev_consume_skb_any in next version.
>
> > +/**
> > + * axienet_start_xmit_dmaengine - Starts the transmission.
> > + * @skb: sk_buff pointer that contains data to be Txed.
> > + * @ndev: Pointer to net_device structure.
> > + *
> > + * Return: NETDEV_TX_OK on success or any non space errors.
> > + * NETDEV_TX_BUSY when free element in TX skb ring buffer
> > + * is not available.
> > + *
> > + * This function is invoked from xmit to initiate transmission. The
> > + * function sets the skbs, register dma call back API and submit
> > + * the dma transaction.
> > + * Additionally if checksum offloading is supported,
> > + * it populates AXI Stream Control fields with appropriate values.
> > + */
> > +static netdev_tx_t
> > +axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device
> > +*ndev) {
> > + struct dma_async_tx_descriptor *dma_tx_desc = NULL;
> > + struct axienet_local *lp = netdev_priv(ndev);
> > + struct skbuf_dma_descriptor *skbuf_dma;
> > + u32 app_metadata[DMA_NUM_APP_WORDS] = {0};
> > + u32 csum_start_off;
> > + u32 csum_index_off;
> > + int sg_len;
> > + int ret;
> > +
> > + sg_len = skb_shinfo(skb)->nr_frags + 1;
> > + if (!CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail,
> TX_BD_NUM_MAX)) {
> > + netif_stop_queue(ndev);
> > + if (net_ratelimit())
> > + netdev_warn(ndev, "TX ring unexpectedly full\n");
>
> I don't see you stopping the queue when the ring gets full, am I not looking
> into the right place? Otherwise this is sort of expected to occasionally hapen
We are calling stop_queue if TX ring is full. Is that what you meant?
netif_stop_queue(ndev);
>
> > + return NETDEV_TX_BUSY;
> > + }
> > +
> > + skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_head);
> > + if (!skbuf_dma)
> > + return NETDEV_TX_OK;
>
> Leaks the skb?
Accepted. Will add dev_kfree_skb in this and below TX_OK error path and
also increment stats.tx_errors++.
>
> > + lp->tx_ring_head++;
> > + sg_init_table(skbuf_dma->sgl, sg_len);
> > + ret = skb_to_sgvec(skb, skbuf_dma->sgl, 0, skb->len);
> > + if (ret < 0)
> > + return NETDEV_TX_OK;
> > +
> > + ret = dma_map_sg(lp->dev, skbuf_dma->sgl, sg_len,
> DMA_TO_DEVICE);
> > + if (!ret)
> > + return NETDEV_TX_OK;
> > +
> > + /* Fill up app fields for checksum */
> > + if (skb->ip_summed == CHECKSUM_PARTIAL) {
> > + if (lp->features & XAE_FEATURE_FULL_TX_CSUM) {
> > + /* Tx Full Checksum Offload Enabled */
> > + app_metadata[0] |= 2;
> > + } else if (lp->features & XAE_FEATURE_PARTIAL_TX_CSUM) {
> > + csum_start_off = skb_transport_offset(skb);
> > + csum_index_off = csum_start_off + skb-
> >csum_offset;
> > + /* Tx Partial Checksum Offload Enabled */
> > + app_metadata[0] |= 1;
> > + app_metadata[1] = (csum_start_off << 16) |
> csum_index_off;
> > + }
> > + } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
> > + app_metadata[0] |= 2; /* Tx Full Checksum Offload Enabled
> */
> > + }
> > +
> > + dma_tx_desc = lp->tx_chan->device->device_prep_slave_sg(lp-
> >tx_chan,
> > +skbuf_dma->sgl,
>
> Possibly store the device_prep_slave_sg pointer to a temporary variable to
> make this line less painfully long?
Will modify in next version.
>
> > + skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_head);
> > + if (!skbuf_dma)
> > + return -ENOMEM;
> > + lp->rx_ring_head++;
> > + skb = netdev_alloc_skb(ndev, lp->max_frm_size);
> > + if (!skb)
> > + return -ENOMEM;
> > +
> > + sg_init_table(skbuf_dma->sgl, 1);
> > + addr = dma_map_single(lp->dev, skb->data, lp->max_frm_size,
> DMA_FROM_DEVICE);
> > + if (unlikely(dma_mapping_error(lp->dev, addr))) {
> > + netdev_err(ndev, "DMA mapping error\n");
>
> needs rate limiting
Agree. Will change it to rate limit call.
>
> > + ret = -ENOMEM;
> > + goto rx_submit_err_free_skb;
>
> is it legal to unmap dma error ?
Will fix this error handling in next version.
>
> > + }
> > + sg_dma_address(skbuf_dma->sgl) = addr;
> > + sg_dma_len(skbuf_dma->sgl) = lp->max_frm_size;
> > + dma_rx_desc = dmaengine_prep_slave_sg(lp->rx_chan, skbuf_dma-
> >sgl,
> > + 1, DMA_DEV_TO_MEM,
> > + DMA_PREP_INTERRUPT);
>
> > +/**
> > + * axienet_init_dmaengine - init the dmaengine code.
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * Return: 0, on success.
> > + * non-zero error value on failure
> > + *
> > + * This is the dmaengine initialization code.
> > + */
> > +static int axienet_init_dmaengine(struct net_device *ndev) {
> > + struct axienet_local *lp = netdev_priv(ndev);
> > + struct skbuf_dma_descriptor *skbuf_dma;
> > + int i, ret;
> > +
> > + lp->tx_chan = dma_request_chan(lp->dev, "tx_chan0");
> > + if (IS_ERR(lp->tx_chan)) {
> > + ret = PTR_ERR(lp->tx_chan);
> > + return dev_err_probe(lp->dev, ret, "No Ethernet DMA (TX)
> channel
> > +found\n");
>
> Why use dev_err_probe()? This is not on the probe path. If ndo_open fails it
> fails, it won't get retried later by itself, right?
I see , will fix it, and remove _probe variant.
>
> > @@ -1238,7 +1540,24 @@ static int axienet_open(struct net_device
> > *ndev)
> >
> > phylink_start(lp->phylink);
> >
> > - if (!lp->use_dmaengine) {
> > + if (lp->use_dmaengine) {
> > + /* Enable interrupts for Axi Ethernet core (if defined) */
> > + if (lp->eth_irq > 0) {
> > + ret = request_irq(lp->eth_irq, axienet_eth_irq,
> IRQF_SHARED,
> > + ndev->name, ndev);
> > + if (ret)
> > + goto error_code;
> > + }
> > +
> > + ret = axienet_init_dmaengine(ndev);
> > +
>
> pointless new line
Will fix in next version.
>
> > + if (ret < 0) {
> > + if (lp->eth_irq > 0)
> > + free_irq(lp->eth_irq, ndev);
>
> can't this be on the error path?
It's just single instance so didn't introduce error label for it.
But I can move to error path.
>
> > + goto error_code;
> > + }
> > +
>
> pointless new line
Will fix it in next version.
>
> > + } else {
>
> --
> pw-bot: cr
On Fri, 6 Oct 2023 19:04:29 +0000 Pandey, Radhey Shyam wrote:
> > > + netif_stop_queue(ndev);
> > > + if (net_ratelimit())
> > > + netdev_warn(ndev, "TX ring unexpectedly full\n");
> >
> > I don't see you stopping the queue when the ring gets full, am I not looking
> > into the right place? Otherwise this is sort of expected to occasionally hapen
>
> We are calling stop_queue if TX ring is full. Is that what you meant?
> netif_stop_queue(ndev);
But somewhere else or just here after printing the warning?
The recommended flow is to stop the queue after enqueuing
a packet successfully, if the remaining space is not enough
to hold an skb with all frags populated. That avoids ever
returning BUSY.
> -----Original Message-----
> From: Jakub Kicinski <[email protected]>
> Sent: Saturday, October 7, 2023 3:03 AM
> To: Pandey, Radhey Shyam <[email protected]>
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; Simek, Michal <[email protected]>;
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; linux-arm-
> [email protected]; git (AMD-Xilinx) <[email protected]>
> Subject: Re: [PATCH net-next v7 3/3] net: axienet: Introduce dmaengine
> support
>
> On Fri, 6 Oct 2023 19:04:29 +0000 Pandey, Radhey Shyam wrote:
> > > > + netif_stop_queue(ndev);
> > > > + if (net_ratelimit())
> > > > + netdev_warn(ndev, "TX ring unexpectedly full\n");
> > >
> > > I don't see you stopping the queue when the ring gets full, am I not
> > > looking into the right place? Otherwise this is sort of expected to
> > > occasionally hapen
> >
> > We are calling stop_queue if TX ring is full. Is that what you meant?
> > netif_stop_queue(ndev);
>
> But somewhere else or just here after printing the warning?
There is call to netif_stop_queue(ndev) just before this netdev_warn.
I copied below for quick reference.
+ sg_len = skb_shinfo(skb)->nr_frags + 1;
+ if (!CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX)) {
+ netif_stop_queue(ndev);
+ if (net_ratelimit())
+ netdev_warn(ndev, "TX ring unexpectedly full\n");
+ return NETDEV_TX_BUSY;
+ }
However, I noticed above check doesn't account for all frags - so will
modify the if check to see if available space is less than sg_len. If yes, then
stop the queue and return busy , else continue with xmit.
>
> The recommended flow is to stop the queue after enqueuing a packet
> successfully, if the remaining space is not enough to hold an skb with all frags
> populated. That avoids ever returning BUSY.
On 9/27/23 12:32, Radhey Shyam Pandey wrote:
> Add dmaengine framework to communicate with the xilinx DMAengine
> driver(AXIDMA).
>
> Axi ethernet driver uses separate channels for transmit and receive.
> Add support for these channels to handle TX and RX with skb and
> appropriate callbacks. Also add axi ethernet core interrupt for
> dmaengine framework support.
>
> The dmaengine framework was extended for metadata API support.
> However it still needs further enhancements to make it well suited for
> ethernet usecases. The ethernet features i.e ethtool set/get of DMA IP
> properties, ndo_poll_controller,(mentioned in TODO) are not supported
> and it requires follow-up discussions.
>
> dmaengine support has a dependency on xilinx_dma as it uses
> xilinx_vdma_channel_set_config() API to reset the DMA IP
> which internally reset MAC prior to accessing MDIO.
>
> Benchmark with netperf:
>
> xilinx-zcu102-20232:~$ netperf -H 192.168.10.20 -t TCP_STREAM
> MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET
> to 192.168.10.20 () port 0 AF_INET
> Recv Send Send
> Socket Socket Message Elapsed
> Size Size Size Time Throughput
> bytes bytes bytes secs. 10^6bits/sec
>
> 131072 16384 16384 10.03 915.55
>
> xilinx-zcu102-20232:~$ netperf -H 192.168.10.20 -t UDP_STREAM
> MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET
> to 192.168.10.20 () port 0 AF_INET
> Socket Message Elapsed Messages
> Size Size Time Okay Errors Throughput
> bytes bytes secs # # 10^6bits/sec
>
> 212992 65507 10.00 18192 0 953.35
> 212992 10.00 18192 953.35
>
> Signed-off-by: Radhey Shyam Pandey <[email protected]>
> ---
[snip]
> /**
> * axienet_tx_poll - Invoked once a transmit is completed by the
> * Axi DMA Tx channel.
> @@ -911,7 +1036,43 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
> if (!lp->use_dmaengine)
> return axienet_start_xmit_legacy(skb, ndev);
> else
> - return NETDEV_TX_BUSY;
> + return axienet_start_xmit_dmaengine(skb, ndev);
Did not notice this before, but should consider using a separate set of
net_device_ops with a different ndo_start_xmit() implementation, rather
than add another layer of indirection here.
--
Florian
On Mon, 9 Oct 2023 19:41:35 +0000 Pandey, Radhey Shyam wrote:
> > But somewhere else or just here after printing the warning?
>
> There is call to netif_stop_queue(ndev) just before this netdev_warn.
> I copied below for quick reference.
>
> + sg_len = skb_shinfo(skb)->nr_frags + 1;
> + if (!CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX)) {
> + netif_stop_queue(ndev);
> + if (net_ratelimit())
> + netdev_warn(ndev, "TX ring unexpectedly full\n");
> + return NETDEV_TX_BUSY;
> + }
>
> However, I noticed above check doesn't account for all frags - so will
> modify the if check to see if available space is less than sg_len. If yes, then
> stop the queue and return busy , else continue with xmit.
Please take a look at:
https://www.kernel.org/doc/html/next/networking/driver.html#stop-queues-in-advance
> -----Original Message-----
> From: Florian Fainelli <[email protected]>
> Sent: Tuesday, October 10, 2023 1:51 AM
> To: Pandey, Radhey Shyam <[email protected]>;
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; Simek, Michal
> <[email protected]>; [email protected]
> Cc: [email protected]; [email protected]; linux-
> [email protected]; [email protected]; git (AMD-
> Xilinx) <[email protected]>
> Subject: Re: [PATCH net-next v7 3/3] net: axienet: Introduce dmaengine
> support
>
> On 9/27/23 12:32, Radhey Shyam Pandey wrote:
> > Add dmaengine framework to communicate with the xilinx DMAengine
> > driver(AXIDMA).
> >
> > Axi ethernet driver uses separate channels for transmit and receive.
> > Add support for these channels to handle TX and RX with skb and
> > appropriate callbacks. Also add axi ethernet core interrupt for
> > dmaengine framework support.
> >
> > The dmaengine framework was extended for metadata API support.
> > However it still needs further enhancements to make it well suited for
> > ethernet usecases. The ethernet features i.e ethtool set/get of DMA IP
> > properties, ndo_poll_controller,(mentioned in TODO) are not supported
> > and it requires follow-up discussions.
> >
> > dmaengine support has a dependency on xilinx_dma as it uses
> > xilinx_vdma_channel_set_config() API to reset the DMA IP which
> > internally reset MAC prior to accessing MDIO.
> >
> > Benchmark with netperf:
> >
> > xilinx-zcu102-20232:~$ netperf -H 192.168.10.20 -t TCP_STREAM MIGRATED
> > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.10.20
> > () port 0 AF_INET
> > Recv Send Send
> > Socket Socket Message Elapsed
> > Size Size Size Time Throughput
> > bytes bytes bytes secs. 10^6bits/sec
> >
> > 131072 16384 16384 10.03 915.55
> >
> > xilinx-zcu102-20232:~$ netperf -H 192.168.10.20 -t UDP_STREAM
> MIGRATED
> > UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.10.20
> > () port 0 AF_INET
> > Socket Message Elapsed Messages
> > Size Size Time Okay Errors Throughput
> > bytes bytes secs # # 10^6bits/sec
> >
> > 212992 65507 10.00 18192 0 953.35
> > 212992 10.00 18192 953.35
> >
> > Signed-off-by: Radhey Shyam Pandey <[email protected]>
> > ---
> [snip]
> > /**
> > * axienet_tx_poll - Invoked once a transmit is completed by the
> > * Axi DMA Tx channel.
> > @@ -911,7 +1036,43 @@ axienet_start_xmit(struct sk_buff *skb, struct
> net_device *ndev)
> > if (!lp->use_dmaengine)
> > return axienet_start_xmit_legacy(skb, ndev);
> > else
> > - return NETDEV_TX_BUSY;
> > + return axienet_start_xmit_dmaengine(skb, ndev);
>
> Did not notice this before, but should consider using a separate set of
> net_device_ops with a different ndo_start_xmit() implementation, rather
> than add another layer of indirection here.
Thanks, will make it a separate net_device_ops for dmaengine flow and
revert changes in axienet_start_xmit() from 2/3 patch.
Thanks,
Radhey