On Wed, Mar 29, 2017 at 05:48:17PM +0800, Fu Wei wrote:

[...]

 * @platform_timer_count: It points to a integer variable which is used
 *                           for storing the number of platform timers.
 *                           This pointer could be NULL, if the caller
 *                           doesn't need this info.

quoted

quoted

+ *
+ * Return: 0 if success, -EINVAL if error.
+ */
+int __init acpi_gtdt_init(struct acpi_table_header *table,
+                       int *platform_timer_count)
+{
+     int ret = 0;
+     int timer_count = 0;
+     void *platform_timer = NULL;
+     struct acpi_table_gtdt *gtdt;
+
+     gtdt = container_of(table, struct acpi_table_gtdt, header);
+     acpi_gtdt_desc.gtdt = gtdt;
+     acpi_gtdt_desc.gtdt_end = (void *)table + table->length;
+
+     if (table->revision < 2)
+             pr_warn("Revision:%d doesn't support Platform Timers.\n",
+                     table->revision);

Ok, two points here. First, I am not sure why you should warn if the
table revision is < 2, is that a FW bug ? I do not think it is, you
can just return 0.

I used pr_debug here before v20, then I got Hanjun's suggestion:
-------
GTDT table revision is updated to 2 in ACPI 5.1, we will
not support ACPI version under 5.1 and disable ACPI in FADT
parse before this code is called, so if we get revision
<2 here, I think we need to print warning (we need to keep
the firmware stick to the spec on ARM64).
-------
https://lkml.org/lkml/2017/1/19/82

So I started to use pr_warn.

Thanks for the explanation, so it is a FW bug and the warning
is granted :) just leave it there.

Still, please check my comment on acpi_gtdt_init() being called
multiple times on patch 11.

Thanks,
Lorenzo