From 2a908002c7b1b666616103e9df2419b38d7c6f1f Mon Sep 17 00:00:00 2001 From: Frans Pop Date: Wed, 26 Aug 2009 14:29:29 -0700 Subject: ACPI processor: force throttling state when BIOS returns incorrect value If the BIOS reports an invalid throttling state (which seems to be fairly common after system boot), a reset is done to state T0. Because of a check in acpi_processor_get_throttling_ptc(), the reset never actually gets executed, which results in the error reoccurring on every access of for example /proc/acpi/processor/CPU0/throttling. Add a 'force' option to acpi_processor_set_throttling() to ensure the reset really takes effect. Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13389 This patch, together with the next one, fixes a regression introduced in 2.6.30, listed on the regression list. They have been available for 2.5 months now in bugzilla, but have not been picked up, despite various reminders and without any reason given. Google shows that numerous people are hitting this issue. The issue is in itself relatively minor, but the bug in the code is clear. The patches have been in all my kernels and today testing has shown that throttling works correctly with the patches applied when the system overheats (http://bugzilla.kernel.org/show_bug.cgi?id=13918#c14). Signed-off-by: Frans Pop Acked-by: Zhang Rui Cc: Len Brown Cc: "Rafael J. Wysocki" Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/acpi/processor.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include/acpi/processor.h') diff --git a/include/acpi/processor.h b/include/acpi/processor.h index baf1e0a..740ac3a 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -174,7 +174,7 @@ struct acpi_processor_throttling { cpumask_var_t shared_cpu_map; int (*acpi_processor_get_throttling) (struct acpi_processor * pr); int (*acpi_processor_set_throttling) (struct acpi_processor * pr, - int state); + int state, bool force); u32 address; u8 duty_offset; @@ -321,7 +321,8 @@ static inline int acpi_processor_ppc_has_changed(struct acpi_processor *pr) /* in processor_throttling.c */ int acpi_processor_tstate_has_changed(struct acpi_processor *pr); int acpi_processor_get_throttling_info(struct acpi_processor *pr); -extern int acpi_processor_set_throttling(struct acpi_processor *pr, int state); +extern int acpi_processor_set_throttling(struct acpi_processor *pr, + int state, bool force); extern const struct file_operations acpi_processor_throttling_fops; extern void acpi_processor_throttling_init(void); /* in processor_idle.c */ -- cgit v1.1