On 19/08/14 11:39, Hanjun Guo wrote:
On 2014-8-19 2:32, Sudeep Holla wrote:
On 04/08/14 16:28, 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.
The latter selects the appropriate conduit for PSCI calls by
toggling between Hypervisor Calls (HVC) and Secure Monitor Calls
(SMC).
FADT table contains such information, parse FADT to get the flags
for PSCI init. Since ACPI 5.1 doesn't support self defined PSCI
function IDs, which means that only PSCI 0.2+ is supported in ACPI.
At the same time, only ACPI 5.1 or higher verison supports PSCI,
and FADT Major.Minor version was introduced in ACPI 5.1, so we
will check the version and only parse FADT table with version >= 5.1.
If firmware provides ACPI tables with ACPI version less than 5.1,
OS will be messed up with those information and have no way to
bring up secondery CPUs, so disable ACPI if we get an FADT table
with version less that 5.1.
[...]
+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) {
&&
Catalin also pointed out this bug :), but && is not enough, for example,
this would not trigger of revision 4.1, although 4.1 is not exist, but
the code will still confusing people, so I updated the code as:
Right I missed it :), the below code looks fine.
+ 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();
As suggested elsewhere try to eliminate this and have it once if
acpi_boot_init failed for any reasons.
Regards,
Sudeep
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