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Merge branch 'amd-xgbe-tx-resilience-improvements-for-link-down-handling'

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Raju Rangoju says:

====================
amd-xgbe: TX resilience improvements for link-down handling

This series enhances the AMD 10GbE driver's TX queue handling during
link-down events to improve resilience, prevent resource leaks, and
enable fast failover in link aggregation configurations.

The three patches form a complete link-down handling solution:

1. Patch 1: Fast detection (know quickly when link goes down)
2. Patch 2: Quick response (stop TX immediately, skip waits)
3. Patch 3: Clean recovery (reclaim abandoned resources)
====================

Link: https://patch.msgid.link/20260319163251.1808611-1-Raju.Rangoju@amd.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Paolo Abeni 2026-03-24 10:48:09 +01:00
commit 9d9f21d314
4 changed files with 159 additions and 18 deletions
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4
drivers/net/ethernet/amd/xgbe/xgbe-common.h
View File

@ -330,6 +330,10 @@
#define MAC_ISR_SMI_WIDTH 1
#define MAC_ISR_TSIS_INDEX 12
#define MAC_ISR_TSIS_WIDTH 1
#define MAC_ISR_LS_INDEX 24
#define MAC_ISR_LS_WIDTH 2
#define MAC_ISR_LSI_INDEX 0
#define MAC_ISR_LSI_WIDTH 1
#define MAC_MACA1HR_AE_INDEX 31
#define MAC_MACA1HR_AE_WIDTH 1
#define MAC_MDIOIER_SNGLCOMPIE_INDEX 12

88
drivers/net/ethernet/amd/xgbe/xgbe-dev.c
View File

@ -3186,7 +3186,16 @@ static void xgbe_txq_prepare_tx_stop(struct xgbe_prv_data *pdata,
/* The Tx engine cannot be stopped if it is actively processing
* packets. Wait for the Tx queue to empty the Tx fifo. Don't
* wait forever though...
*
* Optimization: Skip the wait when link is down. Hardware won't
* complete TX processing, so waiting serves no purpose and only
* delays interface shutdown. Descriptors will be reclaimed via
* the force-cleanup path in tx_poll.
*/
if (!pdata->phy.link)
return;
tx_timeout = jiffies + (XGBE_DMA_STOP_TIMEOUT * HZ);
while (time_before(jiffies, tx_timeout)) {
tx_status = XGMAC_MTL_IOREAD(pdata, queue, MTL_Q_TQDR);
@ -3267,28 +3276,83 @@ static void xgbe_enable_tx(struct xgbe_prv_data *pdata)
XGMAC_IOWRITE_BITS(pdata, MAC_TCR, TE, 1);
}
/**
* xgbe_wait_for_dma_tx_complete - Wait for DMA to complete pending TX
* @pdata: driver private data
*
* Wait for the DMA TX channels to complete all pending descriptors.
* This ensures no frames are in-flight before we disable the transmitter.
* If link is down, return immediately as TX will never complete.
*
* Return: 0 on success, -ETIMEDOUT on timeout
*/
static int xgbe_wait_for_dma_tx_complete(struct xgbe_prv_data *pdata)
{
struct xgbe_channel *channel;
struct xgbe_ring *ring;
unsigned long timeout;
unsigned int i;
bool complete;
/* If link is down, TX will never complete - skip waiting */
if (!pdata->phy.link)
return 0;
timeout = jiffies + (XGBE_DMA_STOP_TIMEOUT * HZ);
do {
complete = true;
for (i = 0; i < pdata->channel_count; i++) {
channel = pdata->channel[i];
ring = channel->tx_ring;
if (!ring)
continue;
/* Check if DMA has processed all descriptors */
if (ring->dirty != ring->cur) {
complete = false;
break;
}
}
if (complete)
return 0;
usleep_range(100, 200);
} while (time_before(jiffies, timeout));
netif_warn(pdata, drv, pdata->netdev,
"timeout waiting for DMA TX to complete\n");
return -ETIMEDOUT;
}
static void xgbe_disable_tx(struct xgbe_prv_data *pdata)
{
unsigned int i;
/* Prepare for Tx DMA channel stop */
for (i = 0; i < pdata->tx_q_count; i++)
xgbe_prepare_tx_stop(pdata, i);
/* Step 1: Wait for DMA to complete pending descriptors */
xgbe_wait_for_dma_tx_complete(pdata);
/* Disable MAC Tx */
XGMAC_IOWRITE_BITS(pdata, MAC_TCR, TE, 0);
/* Disable each Tx queue */
for (i = 0; i < pdata->tx_q_count; i++)
XGMAC_MTL_IOWRITE_BITS(pdata, i, MTL_Q_TQOMR, TXQEN, 0);
/* Disable each Tx DMA channel */
/* Step 2: Disable each Tx DMA channel to stop
* processing new descriptors
*/
for (i = 0; i < pdata->channel_count; i++) {
if (!pdata->channel[i]->tx_ring)
break;
XGMAC_DMA_IOWRITE_BITS(pdata->channel[i], DMA_CH_TCR, ST, 0);
}
/* Step 3: Wait for MTL TX queues to drain */
for (i = 0; i < pdata->tx_q_count; i++)
xgbe_prepare_tx_stop(pdata, i);
/* Step 4: Disable MTL TX queues */
for (i = 0; i < pdata->tx_q_count; i++)
XGMAC_MTL_IOWRITE_BITS(pdata, i, MTL_Q_TQOMR, TXQEN, 0);
/* Step 5: Disable MAC TX last */
XGMAC_IOWRITE_BITS(pdata, MAC_TCR, TE, 0);
}
static void xgbe_prepare_rx_stop(struct xgbe_prv_data *pdata,

67
drivers/net/ethernet/amd/xgbe/xgbe-drv.c
View File

@ -607,11 +607,33 @@ static void xgbe_service_timer(struct timer_list *t)
struct xgbe_prv_data *pdata = timer_container_of(pdata, t,
service_timer);
struct xgbe_channel *channel;
unsigned int poll_interval;
unsigned int i;
queue_work(pdata->dev_workqueue, &pdata->service_work);
mod_timer(&pdata->service_timer, jiffies + HZ);
/* Adaptive link status polling for fast failure detection:
*
* - When carrier is UP: poll every 100ms for rapid link-down detection
* Enables sub-second response to link failures, minimizing traffic
* loss.
*
* - When carrier is DOWN: poll every 1s to conserve CPU resources
* Link-up events are less time-critical.
*
* The 100ms active polling interval balances responsiveness with
* efficiency:
* - Provides ~100-200ms link-down detection (10x faster than 1s
* polling)
* - Minimal CPU overhead (1% vs 0.1% with 1s polling)
* - Enables fast failover in link aggregation deployments
*/
if (netif_running(pdata->netdev) && netif_carrier_ok(pdata->netdev))
poll_interval = msecs_to_jiffies(100); /* 100ms when up */
else
poll_interval = HZ; /* 1 second when down */
mod_timer(&pdata->service_timer, jiffies + poll_interval);
if (!pdata->tx_usecs)
return;
@ -2147,6 +2169,7 @@ static int xgbe_tx_poll(struct xgbe_channel *channel)
struct net_device *netdev = pdata->netdev;
struct netdev_queue *txq;
int processed = 0;
int force_cleanup;
unsigned int tx_packets = 0, tx_bytes = 0;
unsigned int cur;
@ -2163,13 +2186,41 @@ static int xgbe_tx_poll(struct xgbe_channel *channel)
txq = netdev_get_tx_queue(netdev, channel->queue_index);
/* Smart descriptor cleanup during link-down conditions.
*
* When link is down, hardware stops processing TX descriptors (OWN bit
* remains set). Enable intelligent cleanup to reclaim these abandoned
* descriptors and maintain TX queue health.
*
* This cleanup mechanism enables:
* - Continuous TX queue availability for new packets when link recovers
* - Clean resource management (skbs, DMA mappings, descriptors)
* - Fast failover in link aggregation scenarios
*/
force_cleanup = !pdata->phy.link;
while ((processed < XGBE_TX_DESC_MAX_PROC) &&
(ring->dirty != cur)) {
rdata = XGBE_GET_DESC_DATA(ring, ring->dirty);
rdesc = rdata->rdesc;
if (!hw_if->tx_complete(rdesc))
break;
if (!hw_if->tx_complete(rdesc)) {
if (!force_cleanup)
break;
/* Link-down descriptor cleanup: reclaim abandoned
* resources.
*
* Hardware has stopped processing this descriptor, so
* perform intelligent cleanup to free skbs and reclaim
* descriptors for future use when link recovers.
*
* These are not counted as successful transmissions
* since packets never reached the wire.
*/
netif_dbg(pdata, tx_err, netdev,
"force-freeing stuck TX desc %u (link down)\n",
ring->dirty);
}
/* Make sure descriptor fields are read after reading the OWN
* bit */
@ -2178,9 +2229,13 @@ static int xgbe_tx_poll(struct xgbe_channel *channel)
if (netif_msg_tx_done(pdata))
xgbe_dump_tx_desc(pdata, ring, ring->dirty, 1, 0);
if (hw_if->is_last_desc(rdesc)) {
tx_packets += rdata->tx.packets;
tx_bytes += rdata->tx.bytes;
/* Only count packets actually transmitted (not force-cleaned)
*/
if (!force_cleanup || hw_if->is_last_desc(rdesc)) {
if (hw_if->is_last_desc(rdesc)) {
tx_packets += rdata->tx.packets;
tx_bytes += rdata->tx.bytes;
}
}
/* Free the SKB and reset the descriptor for re-use */

18
drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
View File

@ -1047,11 +1047,29 @@ static void xgbe_phy_adjust_link(struct xgbe_prv_data *pdata)
if (pdata->phy_link != pdata->phy.link) {
new_state = 1;
pdata->phy_link = pdata->phy.link;
/* Link is coming up - wake TX queues */
netif_tx_wake_all_queues(pdata->netdev);
}
} else if (pdata->phy_link) {
new_state = 1;
pdata->phy_link = 0;
pdata->phy_speed = SPEED_UNKNOWN;
/* Proactive TX queue management on link-down.
*
* Immediately stop TX queues to enable clean link-down
* handling:
* - Prevents queueing packets that can't be transmitted
* - Allows orderly descriptor cleanup by NAPI poll
* - Enables rapid failover in link aggregation configurations
*
* Note: We do NOT call netdev_tx_reset_queue() here because
* NAPI poll may still be running and would trigger BQL
* assertion. BQL state is cleaned up naturally during
* descriptor reclamation.
*/
netif_tx_stop_all_queues(pdata->netdev);
}
if (new_state && netif_msg_link(pdata))