Re: [v5,4/4] stmmac: s32: enable support for Multi-IRQ mode
flat view
From: Simon Horman <horms@kernel.org>
Date: 2026-02-25 09:25:22
Also in:
imx, linux-arm-kernel, linux-devicetree, lkml
This is an AI-generated review of your patch. The human sending this email has considered the AI review valid, or at least plausible. For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html --- stmmac: s32: enable support for Multi-IRQ mode This commit enables Multi-IRQ mode for the S32 DWMAC driver, allowing per-queue IRQs for improved performance. The driver checks for multiple queues and per-queue IRQs, enabling multi-IRQ mode when both are present.
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c index af594a096676..4aad7077c9d6 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c
[ ... ]
quoted hunk ↗ jump to hunk
@@ -165,6 +165,16 @@ static int s32_dwmac_probe(struct platform_device *pdev) plat->core_type = DWMAC_CORE_GMAC4; plat->pmt = 1; plat->flags |= STMMAC_FLAG_SPH_DISABLE; + + /* Check for multi-IRQ config. Assumption: symmetrical rx/tx queues */ + if (plat->rx_queues_to_use > 1 && + (res.rx_irq[0] > 0 && res.tx_irq[0] > 0)) { + plat->flags |= STMMAC_FLAG_MULTI_MSI_EN; + dev_info(dev, "Multi-IRQ mode (per queue IRQs) selected\n"); + } else { + dev_info(dev, "MAC IRQ mode selected\n"); + }
Does this validation check all queues have IRQs? The condition verifies
only res.rx_irq[0] and res.tx_irq[0] but doesn't confirm that higher
queues have IRQs when rx_queues_to_use > 1.
If a device tree specifies multiple queues but only provides IRQs for
queue 0:
snps,rx-queues-to-use = <2>;
interrupt-names = "macirq", "rx-queue-0", "tx-queue-0";
/* queue 1 IRQs missing */
The driver would enable STMMAC_FLAG_MULTI_MSI_EN, but later in
stmmac_request_irq_multi_msi() (drivers/net/ethernet/stmicro/stmmac/
stmmac_main.c), queues with rx_irq[i] == 0 are silently skipped:
for (i = 0; i < priv->plat->rx_queues_to_use; i++) {
if (priv->rx_irq[i] <= 0)
continue; /* queue 1+ skipped, no handler registered */
...
}
This would leave higher-numbered queues with no interrupt handler,
causing packet loss when traffic arrives on those queues.
Would it be safer to validate all queue IRQs before enabling multi-IRQ
mode, or fall back to MAC IRQ mode if any queue IRQ is missing?
quoted hunk ↗ jump to hunk
+ plat->rx_fifo_size = 20480; plat->tx_fifo_size = 20480;