On 10/19/2012 11:50 PM, Julius Werner wrote:
> When cpuidle drivers do not supply explicit power_usage values,
> cpuidle/driver.c inserts dummy values instead. When a running processor
> dynamically gains new C-states (e.g. after ACPI events), the power_usage
> values of those states will stay uninitialized, and cpuidle governors
> will never choose to enter them.
>
> This patch ensures that the ACPI cpuidle driver sets those dummy power
> values itself whenever it (re-)initializes its idle states.
> Tested and verified on an Acer AC700 Chromebook, which supports the C3
> state only when it switches from AC to battery power.
>
> Signed-off-by: Julius Werner <jwer...@chromium.org>
> ---
I am not against this patch but I am wondering if it is not time to do
some cleanup around this.
The flag 'power_specified' is never used in any driver.
And the field 'power_usage' is used only in the tegra3 driver where
logically as power_specified is not set, it will be overwritten at the
init (could someone could check the
/sys/devices/system/cpu/cpu0/cpuidle/state1/power is different from 600
on tegra3 ?)
The drivers define their states in a power consumption descendant order
making de facto the same ordering than the 'set_power_state' function in
driver.c
The governor looks at the power_usage (which is always filled by
'set_power_state').
static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device
*dev)
[ ... ]
if (s->power_usage < power_usage) {
power_usage = s->power_usage;
data->last_state_idx = i;
data->exit_us = s->exit_latency;
}
[ ... ]
Could we just say this is always true because state[i+1] consumes less
than state[i] ?
And then just remove the 'set_power_state' function, and the field
'driver->power_specified' ?
That will cleanup the code and fix this problem, no ?
Thanks
-- Daniel
> drivers/acpi/processor_idle.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index e8086c7..078e22f 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -1090,6 +1090,9 @@ static int acpi_processor_setup_cpuidle_states(struct
> acpi_processor *pr)
> state->exit_latency = cx->latency;
> state->target_residency = cx->latency * latency_factor;
>
> + /* reinitialize this in case new states are added after boot */
> + state->power_usage = -1 - count;
> +
> state->flags = 0;
> switch (cx->type) {
> case ACPI_STATE_C1:
--
<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-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
