On 2014-8-18 22:27, Catalin Marinas wrote:

On Mon, Aug 04, 2014 at 04:28:12PM +0100, Hanjun Guo wrote:

quoted

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.

quoted

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.

quoted

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;
+       }

quoted

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.

quoted

 	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