Re: RE: Re:RE: [PATCH] pinctrl: mcp23s08: reject devices without match data

[Andy Shevchenko]

On Thu, Oct 01, 2026 at 10:07:29PM +0200, Linus Walleij wrote:
> On Mon, Sep 28, 2026 at 9:25 AM jiale yao <19888972804@xxxxxxx> wrote:
> 
> > I reproduced this deterministically with KASAN on arm64 QEMU.
> > The SPI device has an unmatched compatible and a valid microchip,spi-present-mask property, and is then bound with:
> >
> > echo mcp23s08 > /sys/bus/spi/devices/spi0.0/driver_override
> > echo spi0.0 > /sys/bus/spi/drivers/mcp23s08/bind
> 
> [KASAN splat from spi_get_device_match_data() returning NULL]
> 
> But hey look in the driver:
> 
> static const struct spi_device_id mcp23s08_ids[] = {
>         { "mcp23s08", (kernel_ulong_t)&mcp23s08_spi },
>         { "mcp23s17", (kernel_ulong_t)&mcp23s17_spi },
>         { "mcp23s18", (kernel_ulong_t)&mcp23s18_spi },
>         { }
> };
> MODULE_DEVICE_TABLE(spi, mcp23s08_ids);
> 
> Why doesn't the override find the right data from the match table?
> 
> This looks more like a bug in the SPI bus implementation,
> surely the bus should match a driver_overrid and return a
> valid match data from spi_get_device_match_data()?
> 
> I think this is just papering over the real issue, you need
> to dig into the SPI bus implementation and see why this isn't
> working.

I believe this is the whole design of driver_override like this...
There is an attempt to allow drivers to forbid that feature.

-- 
With Best Regards,
Andy Shevchenko