On 2014-8-18 22:27, Catalin Marinas wrote:
> On Mon, Aug 04, 2014 at 04:28:12PM +0100, Hanjun Guo wrote:
>> There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set,
>> the former signals to the OS that the hardware is PSCI compliant.
>
> Actually it signals that the firmware is PSCI compliant. The hardware
> doesn't care much.
Right, I will update it.
>
>> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
>> index 6400312..6e04868 100644
>> --- a/arch/arm64/include/asm/acpi.h
>> +++ b/arch/arm64/include/asm/acpi.h
>> @@ -19,6 +19,18 @@ extern int acpi_disabled;
>> extern int acpi_noirq;
>> extern int acpi_pci_disabled;
>>
>> +/* 1 to indicate PSCI 0.2+ is implemented */
>> +static inline bool acpi_psci_present(void)
>> +{
>> + return !!(acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT);
>> +}
>> +
>> +/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
>> +static inline bool acpi_psci_use_hvc(void)
>> +{
>> + return !!(acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC);
>> +}
>
> Do we actually need !! here? Shouldn't the compiler figure out
> conversion to bool automatically?
I thought !! will explicitly show that it's a bool value and
improve the readability of the code, but I'm ok to remove !!
here.
>
>> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
>> index 9cf9127..69a315d 100644
>> --- a/arch/arm64/kernel/acpi.c
>> +++ b/arch/arm64/kernel/acpi.c
>> @@ -11,6 +11,8 @@
>> * published by the Free Software Foundation.
>> */
>>
>> +#define pr_fmt(fmt) "ACPI: " fmt
>> +
>> #include <linux/init.h>
>> #include <linux/acpi.h>
>> #include <linux/cpumask.h>
>> @@ -47,6 +49,26 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
>> early_memunmap(map, size);
>> }
>>
>> +static int __init acpi_parse_fadt(struct acpi_table_header *table)
>> +{
>> + struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
>> +
>> + /*
>> + * Revision in table header is the FADT Major version,
>> + * and there is a minor version of FADT which was introduced
>> + * by ACPI 5.1, we only deal with ACPI 5.1 or higher version
>> + * to get arm boot flags, or we will disable ACPI.
>> + */
>> + if (table->revision < 5 || fadt->minor_revision < 1) {
>
> If we ever get revision 6.0, this would trigger.
Yes, good catch, actually I already fixed that in my local git repo,
+ if (table->revision > 5 ||
+ (table->revision == 5 && fadt->minor_revision >= 1)) {
+ return 0;
+ } else {
+ pr_info("FADT revision is %d.%d, no PSCI support, should be 5.1
or higher\n",
+ table->revision, fadt->minor_revision);
+ disable_acpi();
+ return -EINVAL;
+ }
>
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index 85c6326..dfc4e4f3 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -395,6 +395,8 @@ void __init setup_arch(char **cmdline_p)
>> efi_idmap_init();
>>
>> cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
>> + acpi_boot_init();
>> +
>> unflatten_device_tree();
>
> Unless that's changed in a subsequent patch, do we still need to call
> unflatten_device_tree() if ACPI was successful?
No, we don't. in [PATCH v2 16/18], we will not call unflatten_device_tree()
if ACPI is successful. Since the CONFIG_ACPI is not enabled for ARM64 (will
enable it in the last patch), so acpi_boot_init() is a stub empty function
here.
>
>> psci_init();
>
> I would also rename this to something like psci_dt_init() and move the
> acpi_disabled check here rather than in the callee.
thanks for the suggestion, I will update my patch :)
Thanks
Hanjun
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