Re: [PATCH net] net: stmmac: Clear DMA errors for multi-channel interrupts
flat view
From: Lorenzo Bianconi <hidden>
Date: 2026-10-30 12:32:42
Also in:
linux-arm-kernel, lkml
The Multi-MSI interrupt handler doesn't clear the DMA error interrupts,
and this leads to interrupt storms when one of these interrupts starts
firing :
- The RBU (rx buff unav) which triggers under high traffic load
This triggers easily with iperf3 and small udp packets, and shows
when running the netpoll kselftest
- The RPS (rx process stop) which triggers when we stop the DMA RX.
This one shows when restarting the RX logic without doing a down/up
cycle, like when attaching an XDP program. The XSK kselftests
triggers it.
Let's make sure we clear these interrupts for multi-MSI cases. It's
already properly done for the single-chan interrupt, and for that
introduce an "ERR" DMA dir, as we don't want to touch the RI/TI bits
when handling these interrupts.
To avoid duplication, the DMA TX error handling is factored out in a
dedicated helper (in the same commit to ease backporting).
Both of the above storms have been found on dwmac-motorcomm (YT8601),
and are triggered by the xdp.py, xsk_reconfig.py, xdp_features.py,
ring_reconfig.py and netpoll_basic kernel selftests.
This seems to only affect dwmac4, there's no multi-msi mode on
dwmac1000, and on dwxgmac these interrupts are masked as of today.
Fixes: 6ccf12ae111e ("net: stmmac: use interrupt mode INTM=1 for multi-MSI")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>Reviewed-by: Lorenzo Bianconi <redacted>
quoted hunk ↗ jump to hunk
--- drivers/net/ethernet/stmicro/stmmac/common.h | 1 + .../net/ethernet/stmicro/stmmac/dwmac4_dma.h | 5 ++ .../net/ethernet/stmicro/stmmac/dwmac4_lib.c | 2 + .../net/ethernet/stmicro/stmmac/stmmac_main.c | 46 +++++++++++++------ 4 files changed, 40 insertions(+), 14 deletions(-)diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h index c74bc7c9750e..a972bee66504 100644 --- a/drivers/net/ethernet/stmicro/stmmac/common.h +++ b/drivers/net/ethernet/stmicro/stmmac/common.h@@ -382,6 +382,7 @@ enum dma_irq_dir { DMA_DIR_RX = 0x1, DMA_DIR_TX = 0x2, DMA_DIR_RXTX = 0x3, + DMA_DIR_ERR = 0x4, }; enum request_irq_err {diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h index 43b036d4e95b..a7caac3c98e6 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h@@ -173,6 +173,11 @@ static inline u32 dma_chanx_base_addr(const struct dwmac4_addrs *addrs, DMA_CHAN_STATUS_TI | \ DMA_CHAN_STATUS_MSK_COMMON) +#define DMA_CHAN_STATUS_MSK_ERR (DMA_CHAN_STATUS_AIS | \ + DMA_CHAN_STATUS_FBE | \ + DMA_CHAN_STATUS_RPS | \ + DMA_CHAN_STATUS_RBU) + int dwmac4_dma_reset(void __iomem *ioaddr); void dwmac4_enable_dma_irq(struct stmmac_priv *priv, void __iomem *ioaddr, u32 chan, bool rx, bool tx);diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c index a0249715fafa..02aa1a3dd1e2 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c@@ -150,6 +150,8 @@ int dwmac4_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr, intr_status &= DMA_CHAN_STATUS_MSK_RX; else if (dir == DMA_DIR_TX) intr_status &= DMA_CHAN_STATUS_MSK_TX; + else if (dir == DMA_DIR_ERR) + intr_status &= DMA_CHAN_STATUS_MSK_ERR; /* ABNORMAL interrupts */ if (unlikely(intr_status & DMA_CHAN_STATUS_AIS)) {diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 9ded31150fbe..2068b57df8d5 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c@@ -3141,6 +3141,16 @@ static int stmmac_napi_check(struct stmmac_priv *priv, u32 chan, u32 dir) return status; } +static void stmmac_dma_tx_error(struct stmmac_priv *priv, u32 chan, int status) +{ + if (unlikely(status & tx_hard_error_bump_tc)) { + /* Try to bump up the dma threshold on this failure */ + stmmac_bump_dma_threshold(priv, chan); + } else if (unlikely(status == tx_hard_error)) { + stmmac_tx_err(priv, chan); + } +} + /** * stmmac_dma_interrupt - DMA ISR * @priv: driver private structure@@ -3165,13 +3175,24 @@ static void stmmac_dma_interrupt(struct stmmac_priv *priv) status[chan] = stmmac_napi_check(priv, chan, DMA_DIR_RXTX); - for (chan = 0; chan < tx_channel_count; chan++) { - if (unlikely(status[chan] & tx_hard_error_bump_tc)) { - /* Try to bump up the dma threshold on this failure */ - stmmac_bump_dma_threshold(priv, chan); - } else if (unlikely(status[chan] == tx_hard_error)) { - stmmac_tx_err(priv, chan); - } + for (chan = 0; chan < tx_channel_count; chan++) + stmmac_dma_tx_error(priv, chan, status[chan]); +} + +static void stmmac_dma_err_interrupt(struct stmmac_priv *priv) +{ + u8 tx_channel_count = priv->plat->tx_queues_to_use; + u8 channels_to_check = max(priv->plat->rx_queues_to_use, + tx_channel_count); + int status; + u8 chan; + + for (chan = 0; chan < channels_to_check; chan++) { + status = stmmac_dma_interrupt_status(priv, priv->ioaddr, + &priv->xstats, chan, + DMA_DIR_ERR); + if (chan < tx_channel_count) + stmmac_dma_tx_error(priv, chan, status); } }@@ -6466,6 +6487,9 @@ static irqreturn_t stmmac_mac_interrupt(int irq, void *dev_id) /* To handle Common interrupts */ stmmac_common_interrupt(priv); + if (priv->plat->core_type == DWMAC_CORE_GMAC4) + stmmac_dma_err_interrupt(priv); + return IRQ_HANDLED; }@@ -6500,13 +6524,7 @@ static irqreturn_t stmmac_msi_intr_tx(int irq, void *data) return IRQ_HANDLED; status = stmmac_napi_check(priv, chan, DMA_DIR_TX); - - if (unlikely(status & tx_hard_error_bump_tc)) { - /* Try to bump up the dma threshold on this failure */ - stmmac_bump_dma_threshold(priv, chan); - } else if (unlikely(status == tx_hard_error)) { - stmmac_tx_err(priv, chan); - } + stmmac_dma_tx_error(priv, chan, status); return IRQ_HANDLED; }-- 2.56.0
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