-Lee, Hekki
+Hans de Goede, Rafael, Laurent, Sakari
Below bug report again reminds me about the "interesting" design of
some ACPI tables in the wild. See below for more.
On Sun, Jun 20, 2021 at 11:36 AM Dominik Brodowski
<linux@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Over a month ago, Andy Shevchenko reported and fixed a NULL pointer
> dereference issue introduced by commit
> 42e59982917a ("mfd: core: Add support for software nodes")
> in v5.13-rc1:
> https://lore.kernel.org/lkml/20210510141552.57045-1-andriy.shevchenko@xxxxxxxxxxxxxxx/
>
> A bisect shows that it is indeed commit 42e59982917a which causes boot to
> fail due to a NULL pointer dereference on my work laptop, where "intel-lpss"
> is bound to
> 00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
> and fails to bind to INT3446:
>
> [ 6.048087] intel-lpss 0000:00:15.0: enabling device (0000 -> 0002)
> [ 6.050625] idma64 idma64.0: Found Intel integrated DMA 64-bit
> [ 6.109112] intel-lpss 0000:00:15.1: enabling device (0000 -> 0002)
> [ 6.111348] idma64 idma64.1: Found Intel integrated DMA 64-bit
> [ 6.172229] intel-lpss 0000:00:15.2: enabling device (0000 -> 0002)
> [ 6.174353] idma64 idma64.2: Found Intel integrated DMA 64-bit
> [ 6.231865] intel-lpss 0000:00:15.3: enabling device (0000 -> 0002)
> [ 6.233845] idma64 idma64.3: Found Intel integrated DMA 64-bit
> [ 6.287492] ACPI Warning: SystemMemory range 0x00000000FE028000-0x00000000FE0281FF conflicts with OpRegion 0x00000000FE028000-0x00000000FE028207 (\_SB.PCI0.GEXP.BAR0) (20210331/utaddress-204)
> [ 6.287704] ACPI: OSL: Resource conflict; ACPI support missing from driver?
> [ 6.289760] intel-lpss: probe of INT3446:00 failed with error -16
Above lines appear due to the following:
1. In hardware we have an I²C bus with GPIO I/O expander (PCA953x
compatible in all cases I saw so far).
2. The ACPI table has a "real" driver for that expander written in ASL (sic!).
3. Due to the above we have I²C controller resources and that driver
in a conflict, because the driver uses I²C controller registers
directly (sic!).
The questions for brainstorming the ideas here are:
1. Is it possible to blacklist the Device Node from being evaluated /
parsed based on the ACPI DSDT path (the "real driver", of course,
doesn't have any other means to be enumerated properly)?
2. Can we create the ACPI driver in the OS which will take the ACPI
path as ID for enumeration / instantiation?
3. Is it possible to hook up on the methods, so we will know what to
do when a certain method is called (like setting pin direction or so)?
4. Does above make any sense or we simply mark that hardware as broken
(i.e. Windoze-only bad desing) and that's it?
> Unfortunately, the patch by Andy Shevchenko (applied on top of Linus' tree)
> does not fix the issue. A complete revert, however, does fix the issue, and
> allows my laptop to boot again.
>
> In my opinion, it is unfortunate that although it has been known for over a
> month that commit 42e59982917a is broken, the bugfix (though probably not
> far-reaching enough) has not yet progressed upstream.
--
With Best Regards,
Andy Shevchenko
