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@xxxxxxxxxx> >> --- >> 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; >> >> > -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
