Re: [PATCH] ACPI: EC: Look for ECDT EC after calling acpi_load_tables()

[Salvatore Bonaccorso]

Hi,

On Fri, Jun 04, 2021 at 05:22:43PM +0200, Laurențiu Păncescu wrote:
> commit b1c0330823fe upstream.

This should be in any case the full commmit hash as 

"commit b1c0330823fe842dbb34641f1410f0afa51c29d3 upstream."

without shortening.

> Backport of ACPI fix for #199981 for linux-4.9.y, tested on an Asus EeePC
> 1005PE running Debian Buster.
> 
> Some systems have had functional issues since commit 5a8361f7ecce
> (ACPICA: Integrate package handling with module-level code) that,
> among other things, changed the initial values of the
> acpi_gbl_group_module_level_code and acpi_gbl_parse_table_as_term_list
> global flags in ACPICA which implicitly caused acpi_ec_ecdt_probe() to
> be called before acpi_load_tables() on the vast majority of platforms.
> 
> Namely, before commit 5a8361f7ecce, acpi_load_tables() was called from
> acpi_early_init() if acpi_gbl_parse_table_as_term_list was FALSE and
> acpi_gbl_group_module_level_code was TRUE, which almost always was
> the case as FALSE and TRUE were their initial values, respectively.
> The acpi_gbl_parse_table_as_term_list value would be changed to TRUE
> for a couple of platforms in acpi_quirks_dmi_table[], but it remained
> FALSE in the vast majority of cases.
> 
> After commit 5a8361f7ecce, the initial values of the two flags have
> been reversed, so in effect acpi_load_tables() has not been called
> from acpi_early_init() any more.  That, in turn, affects
> acpi_ec_ecdt_probe() which is invoked before acpi_load_tables() now
> and it is not possible to evaluate the _REG method for the EC address
> space handler installed by it.  That effectively causes the EC address
> space to be inaccessible to AML on platforms with an ECDT matching the
> EC device definition in the DSDT and functional problems ensue in
> there.
> 
> Because the default behavior before commit 5a8361f7ecce was to call
> acpi_ec_ecdt_probe() after acpi_load_tables(), it should be safe to
> do that again.  Moreover, the EC address space handler installed by
> acpi_ec_ecdt_probe() is only needed for AML to be able to access the
> EC address space and the only AML that can run during acpi_load_tables()
> is module-level code which only is allowed to access address spaces
> with default handlers (memory, I/O and PCI config space).
> 
> For this reason, move the acpi_ec_ecdt_probe() invocation back to
> acpi_bus_init(), from where it was taken away by commit d737f333b211
> (ACPI: probe ECDT before loading AML tables regardless of module-level
> code flag), and put it after the invocation of acpi_load_tables() to
> restore the original code ordering from before commit 5a8361f7ecce.
> 
> Fixes: 5a8361f7ecce ("ACPICA: Integrate package handling with module-level
> code")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=199981
> Reported-by: step-ali <sunmooon15@xxxxxxxxx>
> Reported-by: Charles Stanhope <charles.stanhope@xxxxxxxxx>
> Tested-by: Charles Stanhope <charles.stanhope@xxxxxxxxx>
> Reported-by: Paulo Nascimento <paulo.ulusu@xxxxxxxxxxxxxx>
> Reported-by: David Purton <dcpurton@xxxxxxxxxxxxxxx>
> Reported-by: Adam Harvey <adam@xxxxxxxxxxxxxxx>
> Reported-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> Tested-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> Tested-by: Jean-Marc Lenoir <archlinux@xxxxxxxxxxx>
> Tested-by: Laurentiu Pancescu <laurentiu@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Laurentiu Pancescu <laurentiu@xxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/acpi/bus.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)

For the rest, but this is more up to the stable maintainers, maybe
though eeds as well comments from the respective maintainers, it might
be an option to make it apply cleanly by first cherry-pick
a46393c02c764a9d8a3e636bfe56f9d2f6f2c397 as well (which fixes a bug on
its own as well).

Cf. https://lore.kernel.org/stable/YLzAw27CQpdEshBl@xxxxxxxxxxx/T/#m6f4a7798eb4f9b0c40e6a10a694c0a6b40ab5044

Regards,
Salvatore