[U-Boot] [PATCH v1 7/7] x86: acpi: Don't touch hardware on HW reduced platforms

[Andy Shevchenko]

On Sat, Jul 22, 2017 at 4:45 PM, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi Andy,
>
> On Sat, Jul 22, 2017 at 3:32 AM, Andy Shevchenko
> <andriy.shevchenko at linux.intel.com> wrote:
>> If ACPI HW reduced bit in FADT is set we should ignore any ACPI hardware
>> communications.
>>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
>> ---
>>  arch/x86/lib/acpi_table.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/x86/lib/acpi_table.c b/arch/x86/lib/acpi_table.c
>> index da6014fb41..3eb101105b 100644
>> --- a/arch/x86/lib/acpi_table.c
>> +++ b/arch/x86/lib/acpi_table.c
>> @@ -463,6 +463,10 @@ ulong write_acpi_tables(ulong start)
>>
>>         debug("ACPI: done\n");
>>
>> +       /* Don't touch ACPI hardware on HW reduced platforms */
>> +       if (fadt->flags & ACPI_FADT_HW_REDUCED_ACPI)
>> +               return current;
>> +
>
> Reviewed-by: Bin Meng <bmeng.cn at gmail.com>

Thanks!

>
> I assume this is needed on Intel Edison.

Actually it has very little with Edison, though I had stumbled over
the bug on that platform.

ARM64 support, if any will come, or I even can suggest to try ASUS
T100 transformer (Baytrail based HW reduced).

> If that's the case, will you
> support S3 resume on Edison? And if yes, I believe we will need update
> acpi_resume() to add the same check there?

It might affect any of HW reduced one, needs to be checked.

I fixed only one issue I found, I didn't look at every places where
U-Boot goes to ACPI HW,

>
>>         /*
>>          * Other than waiting for OSPM to request us to switch to ACPI mode,
>>          * do it by ourselves, since SMI will not be triggered.
>> --
>
> Regards,
> Bin
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-- 
With Best Regards,
Andy Shevchenko