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

On Sun, Jan 25, 2026 at 02:14:05PM -0800, Jakub Kicinski wrote:

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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

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

@@ -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.

The AI is wrong on this statesment. The loop reading IRQs from DT
in stmmac_get_platform_resources() returns also negative value
for missed queue IRQ line. And this is used as flag if multi-IRQ
can be enabled or not.

But I must agree that the comparition shall not include 0 as valid
value for IRQ, so I will fix it in v4.

Thanks.
/Jan