Re: [PATCH v6 3/3] dts: s32g: Add GPR syscon region

[Jared Kangas <jkangas@redhat.com>]

Hi Dan,

On Fri, Jan 30, 2026 at 04:19:52PM +0300, Dan Carpenter wrote:
> Add the GPR syscon region for the s32 chipset.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
>
> [snip]
>
> diff --git a/arch/arm64/boot/dts/freescale/s32g3.dtsi b/arch/arm64/boot/dts/freescale/s32g3.dtsi
> index e314f3c7d61d..be03db737384 100644
> --- a/arch/arm64/boot/dts/freescale/s32g3.dtsi
> +++ b/arch/arm64/boot/dts/freescale/s32g3.dtsi
> @@ -383,6 +383,11 @@ usdhc0-200mhz-grp4 {
>  			};
>  		};
>  
> +		gpr: syscon@4007c000 {
> +			compatible = "nxp,s32g3-gpr", "syscon";
> +			reg = <0x4007c000 0x3000>;
> +		};
> +
>  		ocotp: nvmem@400a4000 {
>  			compatible = "nxp,s32g3-ocotp", "nxp,s32g2-ocotp";
>  			reg = <0x400a4000 0x400>;
> @@ -808,6 +813,7 @@ gmac0: ethernet@4033c000 {
>  			compatible = "nxp,s32g2-dwmac";
>  			reg = <0x4033c000 0x2000>, /* gmac IP */
>  			      <0x4007c004 0x4>;    /* GMAC_0_CTRL_STS */
> +			nxp,phy-sel = <&gpr 0x4>;
>  			interrupt-parent = <&gic>;
>  			interrupts = <GIC_SPI 57 IRQ_TYPE_LEVEL_HIGH>;
>  			interrupt-names = "macirq";

I gave this a test on an S32G-VNP-RDB3 and didn't see any issues on the
dwmac-s32 side, but this appears to trigger a panic when reading the new
debugfs regmap/*/registers file for the syscon node:

    # grep 4007c000 /proc/vmallocinfo
    0xffff800083da8000-0xffff800083dac000   16384 ioremap_prot+0x74/0xe0 phys=0x000000004007c000 ioremap
    # cat /sys/kernel/debug/regmap/dummy-syscon@0x000000004007c000/registers
    Internal error: synchronous external abort: 0000000096000210 [#1]  SMP
    [...]
    CPU: 0 UID: 0 PID: 4344 Comm: cat Tainted: G   M        E  X   ------  ---  6.12.0+ #226 PREEMPT_RT
    Tainted: [M]=MACHINE_CHECK, [E]=UNSIGNED_MODULE, [X]=AUX
    [...]
    pc : regmap_mmio_read32le+0x44/0xa0
    lr : regmap_mmio_read32le+0x44/0xa0
    [...]
    x23: ffff00080c080000 x22: ffff000802ac4c00 x21: ffff800087b13c9c
    x20: ffff800080a46494 x19: ffff800083da810c x18: 0000000000000004
    [...]
    x5 : ffff800080a46448 x4 : ffff800083da8000 x3 : ffff800080a46494
    x2 : ffff800080a47230 x1 : ffff800083da810c x0 : 0000000000000020
    Call trace:
     regmap_mmio_read32le+0x44/0xa0 (P)
     regmap_mmio_read+0x4c/0x80
     [...]
    Code: 52800400 8b214093 aa1303e1 97f4caf0 (b9400275)
    ---[ end trace 0000000000000000 ]---
    Kernel panic - not syncing: synchronous external abort: Fatal exception

Running this through decodecode gives:

    All code
    ========
       0:   52800400        mov     w0, #0x20                       // #32
       4:   8b214093        add     x19, x4, w1, uxtw
       8:   aa1303e1        mov     x1, x19
       c:   97f4caf0        bl      0xffffffffffd32bcc
      10:*  b9400275        ldr     w21, [x19]              <-- trapping instruction

    Code starting with the faulting instruction
    ===========================================
       0:   b9400275        ldr     w21, [x19]

x19's offset from the base address in /proc/vmallocinfo is 0x10c, which
points to a bad read at physical address 0x4007c10c; I also confirmed
that the preceding memory reads back without issues:

    # head -c 990 /sys/kernel/debug/regmap/dummy-syscon@0x000000004007c000/registers | tail -1
    0104: 00000000
    # head -c 1005 /sys/kernel/debug/regmap/dummy-syscon@0x000000004007c000/registers | tail -1
    0108: 00000000
    # head -c 1020 /sys/kernel/debug/regmap/dummy-syscon@0x000000004007c000/registers | tail -1
    <panic>

Best,
Jared