Re: [PATCH net-next v12 4/4] stmmac: s32: enable support for Multi-IRQ mode

On Fri, Mar 13, 2026 at 08:13:35AM +0100, Jan Petrous via B4 Relay wrote:

From: "Jan Petrous (OSS)" <jan.petrous@oss.nxp.com>

Based on previous changes in platform driver, the vendor
glue driver can enable Multi-IRQ mode, if needed.

To get enabled Multi-IRQ mode for dwmac-s32, the driver checks:

  1) property of 'snps,mtl-xx-config' subnode
     defines 'snps,xx-queues-to-use' bigger then one, ie:

     ethernet@4033c000 {
         compatible = "nxp,s32g2-dwmac";
         ...
         snps,mtl-rx-config = <&mtl_rx_setup>;
         ...

         mtl_rx_setup: rx-queues-config {
             snps,rx-queues-to-use = <2>;
         };

  2) queue based IRQs are set, ie:

     ethernet@4033c000 {
         compatible = "nxp,s32g2-dwmac";
         ...
         interrupts = <GIC_SPI 57 IRQ_TYPE_LEVEL_HIGH>,
                      /* CHN 0: tx, rx */
                      <GIC_SPI 58 IRQ_TYPE_LEVEL_HIGH>,
                      <GIC_SPI 59 IRQ_TYPE_LEVEL_HIGH>,
                      /* CHN 1: tx, rx */
                      <GIC_SPI 60 IRQ_TYPE_LEVEL_HIGH>,
                      <GIC_SPI 61 IRQ_TYPE_LEVEL_HIGH>;
         interrupt-names = "macirq",
                           "tx-queue-0", "rx-queue-0",
                           "tx-queue-1", "rx-queue-1";

If those prerequisites are met, the driver switches to Multi-IRQ mode,
using per-queue IRQs for rx/tx data pathr:

[    1.387045] s32-dwmac 4033c000.ethernet: Multi-IRQ mode (per queue IRQs) selected

Now the driver owns all queues IRQs:

root@s32g399aevb3:~# grep eth /proc/interrupts
 29:    0    0    0    0    0    0    0    0    GICv3  89 Level   eth0:mac
 30:    0    0    0    0    0    0    0    0    GICv3  91 Level   eth0:rx-0
 31:    0    0    0    0    0    0    0    0    GICv3  93 Level   eth0:rx-1
 32:    0    0    0    0    0    0    0    0    GICv3  95 Level   eth0:rx-2
 33:    0    0    0    0    0    0    0    0    GICv3  97 Level   eth0:rx-3
 34:    0    0    0    0    0    0    0    0    GICv3  99 Level   eth0:rx-4
 35:    0    0    0    0    0    0    0    0    GICv3  90 Level   eth0:tx-0
 36:    0    0    0    0    0    0    0    0    GICv3  92 Level   eth0:tx-1
 37:    0    0    0    0    0    0    0    0    GICv3  94 Level   eth0:tx-2
 38:    0    0    0    0    0    0    0    0    GICv3  96 Level   eth0:tx-3
 39:    0    0    0    0    0    0    0    0    GICv3  98 Level   eth0:tx-4

Otherwise, if one of the prerequisite don't met, the driver
continue with MAC IRQ mode:

[    1.387045] s32-dwmac 4033c000.ethernet: MAC IRQ mode selected

And only MAC IRQ will be attached:

root@s32g399aevb3:~# grep eth /proc/interrupts
 29:    0    0    0    0    0    0    0    0    GICv3  89 Level   eth0:mac

What represents the original MAC IRQ mode and is fully backward
compatible.

Reviewed-by: Matthias Brugger <mbrugger@suse.com>

Reviewed-by: Russell King (Oracle) <redacted>

Thanks!

-- 
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