Thread (12 messages) 12 messages, 4 authors, 2026-01-27

Re: [v3,4/4] stmmac: s32: enable support for Multi-IRQ mode

From: Jakub Kicinski <kuba@kernel.org>
Date: 2026-01-25 22:14:07
Also in: imx, linux-devicetree, lkml, netdev

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---
stmmac: s32: enable support for Multi-IRQ mode

This patch enables Multi-IRQ mode for the S32 DWMAC driver when both
multi-queue and per-queue IRQs are configured. The driver now selects
between Multi-IRQ and MAC IRQ modes based on device tree configuration.
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 5a485ee98fa7..342091045714 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c
[ ... ]
quoted hunk ↗ jump to hunk
@@ -149,6 +149,16 @@ 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: symetrical rx/tx queues */
+	if (plat->rx_queues_to_use > 1 &&
+	    (res.rx_irq[0] >= 0 || res.tx_irq[0] >= 0)) {
                        ^^^^            ^^^^

Should these checks be "> 0" instead of ">= 0"?

stmmac_get_platform_resources() initializes the res structure with
memset(0), then only writes positive IRQ values when per-queue IRQs are
found in the device tree. If no "rx-queue-0" or "tx-queue-0" interrupt
names are defined, rx_irq[0] and tx_irq[0] remain 0 from the memset.

Since 0 >= 0 evaluates to true, this condition will enable Multi-IRQ
mode even when no per-queue IRQs are available. The commit message states
that "queue based IRQs are set" is a prerequisite, but the current check
does not properly verify this.
+		plat->flags |= STMMAC_FLAG_MULTI_MSI_EN;
+		dev_info(dev, "Multi-IRQ mode (per queue IRQ) selected\n");
[ ... ]
-- 
pw-bot: cr
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