Re: [PATCH] pinctrl: mcp23s08: Disable all pin interrupts during probe

["Uwe Kleine-König" <u.kleine-koenig@baylibre.com>]

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Hello Linus, hello Francesco,

On Tue, Apr 07, 2026 at 08:58:09AM +0200, Linus Walleij wrote:
> On Mon, Mar 30, 2026 at 6:19 PM Francesco Lavra <flavra@baylibre.com> wrote:
> 
> > A chip being probed may have the interrupt-on-change feature enabled on
> > some of its pins, for example after a reboot. This can cause the chip to
> > generate interrupts for pins that don't have a registered nested handler,
> > which leads to a kernel crash such as below:
> >
> > [    7.928897] Unable to handle kernel read from unreadable memory at virtual address 00000000000000ac
> > [    7.932314] Mem abort info:
> > [    7.935081]   ESR = 0x0000000096000004
> > [    7.938808]   EC = 0x25: DABT (current EL), IL = 32 bits
> > [    7.944094]   SET = 0, FnV = 0
> > [    7.947127]   EA = 0, S1PTW = 0
> > [    7.950247]   FSC = 0x04: level 0 translation fault
> > [    7.955101] Data abort info:
> > [    7.957961]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
> > [    7.963421]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
> > [    7.968447]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
> > [    7.973734] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000089b7000
> > [    7.980148] [00000000000000ac] pgd=0000000000000000, p4d=0000000000000000
> > [    7.986913] Internal error: Oops: 0000000096000004 [#1]  SMP
> > [    7.992545] Modules linked in:
> > [    8.073678] CPU: 0 UID: 0 PID: 81 Comm: irq/18-4-0025 Not tainted 7.0.0-rc6-gd2b5a1f931c8-dirty #199
> > [    8.073689] Hardware name: Khadas VIM3 (DT)
> > [    8.073692] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > [    8.094639] pc : _raw_spin_lock_irq+0x40/0x80
> > [    8.098970] lr : handle_nested_irq+0x2c/0x168
> > [    8.098979] sp : ffff800082b2bd20
> > [    8.106599] x29: ffff800082b2bd20 x28: ffff800080107920 x27: ffff800080104d88
> > [    8.106611] x26: ffff000003298080 x25: 0000000000000001 x24: 000000000000ff00
> > [    8.113707] x23: 0000000000000001 x22: 0000000000000000 x21: 000000000000000e
> > [    8.120850] x20: 0000000000000000 x19: 00000000000000ac x18: 0000000000000000
> > [    8.135046] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> > [    8.135062] x14: ffff800081567ea8 x13: ffffffffffffffff x12: 0000000000000000
> > [    8.135070] x11: 00000000000000c0 x10: 0000000000000b60 x9 : ffff800080109e0c
> > [    8.135078] x8 : 1fffe0000069dbc1 x7 : 0000000000000001 x6 : ffff0000034ede00
> > [    8.135086] x5 : 0000000000000000 x4 : ffff0000034ede08 x3 : 0000000000000001
> > [    8.163460] x2 : 0000000000000000 x1 : 0000000000000001 x0 : 00000000000000ac
> > [    8.170560] Call trace:
> > [    8.180094]  _raw_spin_lock_irq+0x40/0x80 (P)
> > [    8.184443]  mcp23s08_irq+0x248/0x358
> > [    8.184462]  irq_thread_fn+0x34/0xb8
> > [    8.184470]  irq_thread+0x1a4/0x310
> > [    8.195093]  kthread+0x13c/0x150
> > [    8.198309]  ret_from_fork+0x10/0x20
> > [    8.201850] Code: d65f03c0 d2800002 52800023 f9800011 (885ffc01)
> > [    8.207931] ---[ end trace 0000000000000000 ]---

I haven't looked in detail but wonder about the the noisy failure which
makes me wonder if there is an(other) issue that is just papered over
here.

Apart from that, it makes totally sense to disable interrupts during
probe.

Best regards
Uwe

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