On Wed, Jun 26, 2019 at 11:37 PM Jeremy Linton <jeremy.linton@xxxxxxx> wrote:
>
> The ACPI specification implies that the IDENTICAL flag should be
> set on all non leaf nodes where the children are identical.
> This means that we need to be searching for the last node with
> the identical flag set rather than the first one.
>
> Since this flag is also dependent on the table revision, we
> need to add a bit of extra code to verify the table revision,
> and the next node's state in the traversal. Since we want to
> avoid function pointers here, lets just special case
> the IDENTICAL flag.
>
> Tested-by: Hanjun Gou <gouhanjun@xxxxxxxxxx>
> Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
Assuming that the Tested-by tag will be fixed:
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/acpi/pptt.c | 35 +++++++++++++++++++++++++++++------
> 1 file changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> index b72e6afaa8fb..05344413f199 100644
> --- a/drivers/acpi/pptt.c
> +++ b/drivers/acpi/pptt.c
> @@ -432,17 +432,40 @@ static void cache_setup_acpi_cpu(struct acpi_table_header *table,
> }
> }
>
> +static bool flag_identical(struct acpi_table_header *table_hdr,
> + struct acpi_pptt_processor *cpu)
> +{
> + struct acpi_pptt_processor *next;
> +
> + /* heterogeneous machines must use PPTT revision > 1 */
> + if (table_hdr->revision < 2)
> + return false;
> +
> + /* Locate the last node in the tree with IDENTICAL set */
> + if (cpu->flags & ACPI_PPTT_ACPI_IDENTICAL) {
> + next = fetch_pptt_node(table_hdr, cpu->parent);
> + if (!(next && next->flags & ACPI_PPTT_ACPI_IDENTICAL))
> + return true;
> + }
> +
> + return false;
> +}
> +
> /* Passing level values greater than this will result in search termination */
> #define PPTT_ABORT_PACKAGE 0xFF
>
> -static struct acpi_pptt_processor *acpi_find_processor_package_id(struct acpi_table_header *table_hdr,
> - struct acpi_pptt_processor *cpu,
> - int level, int flag)
> +static struct acpi_pptt_processor *acpi_find_processor_tag(struct acpi_table_header *table_hdr,
> + struct acpi_pptt_processor *cpu,
> + int level, int flag)
> {
> struct acpi_pptt_processor *prev_node;
>
> while (cpu && level) {
> - if (cpu->flags & flag)
> + /* special case the identical flag to find last identical */
> + if (flag == ACPI_PPTT_ACPI_IDENTICAL) {
> + if (flag_identical(table_hdr, cpu))
> + break;
> + } else if (cpu->flags & flag)
> break;
> pr_debug("level %d\n", level);
> prev_node = fetch_pptt_node(table_hdr, cpu->parent);
> @@ -480,8 +503,8 @@ static int topology_get_acpi_cpu_tag(struct acpi_table_header *table,
>
> cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
> if (cpu_node) {
> - cpu_node = acpi_find_processor_package_id(table, cpu_node,
> - level, flag);
> + cpu_node = acpi_find_processor_tag(table, cpu_node,
> + level, flag);
> /*
> * As per specification if the processor structure represents
> * an actual processor, then ACPI processor ID must be valid.
> --
> 2.21.0
>
