On 09/07/2012 11:50 PM, Rafael J. Wysocki wrote:
On Friday, September 07, 2012, Daniel Lezcano wrote:
The cpuidle core takes care of filling this field from drv->state_count.
I'm not quite sure this is always valid. If dev has already been initialized and dev->state_count is different from 0, cpuidle_enable_device() doesn't actually change it.
Have you considered all of the possible scenarios?
Ok, there is the scenario where the ACPI supports _CST. At runtime, ACPI may notify the OS a C-state changed for a specific cpu and this is done through 'acpi_processor_cst_has_changed' followed by 'acpi_processor_setup_cpuidle_cx'.
So at the end, we could have different cpus with one cpu with less C-states than the other, if I understood correctly ACPIspec30.pdf => page 262 :)
In conclusion, we should keep this variable filled from there and keep this in mind in cpuidle.c in order to not break acpi in the future. Maybe a comment in cpuidle.c would help ... especially with a single C-state registration.
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org
drivers/acpi/processor_idle.c | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 084b1d2..fc4757e 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1035,8 +1035,6 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr) break; }
- dev->state_count = count;
- if (!count) return -EINVAL;