Jean Pihet <jean.pihet@xxxxxxxxxxxxxx> writes:
> When a PM QoS device latency constraint is requested or removed the
> PM QoS layer notifies the underlying layer with the updated aggregated
> constraint value. The constraint is stored in the powerdomain constraints
> list and then applied to the corresponding power domain.
> The power domains get the next power state programmed directly in the
> registers via pwrdm_wakeuplat_update_pwrst.
>
> Tested on OMAP3 Beagleboard and OMAP4 Pandaboard in RET/OFF using
> wake-up latency constraints on MPU, CORE and PER.
>
> Signed-off-by: Jean Pihet <j-pihet@xxxxxx>
[...]
> @@ -191,6 +198,77 @@ static int _pwrdm_post_transition_cb(struct powerdomain *pwrdm, void *unused)
> return 0;
> }
>
> +/**
> + * pwrdm_wakeuplat_update_pwrst - Update power domain power state if needed
> + * @pwrdm: struct powerdomain * to which requesting device belongs to.
> + * @min_latency: the allowed wake-up latency for the given power domain. A
> + * value of PM_QOS_DEV_LAT_DEFAULT_VALUE means 'no constraint' on the pwrdm.
> + *
> + * Finds the power domain next power state that fulfills the constraint.
> + * Programs a new target state if it is different from current power state.
> + * The power domains get the next power state programmed directly in the
> + * registers.
> + *
> + * Returns 0 upon success.
> + */
> +static int pwrdm_wakeuplat_update_pwrst(struct powerdomain *pwrdm,
> + long min_latency)
> +{
> + int ret = 0, new_state = 0;
> +
> + if (!pwrdm) {
> + WARN(1, "powerdomain: %s: invalid parameter(s)", __func__);
> + return -EINVAL;
> + }
> +
> + /*
> + * Apply constraints to power domains by programming
> + * the pwrdm next power state.
> + */
> +
> + /* Find power state with wakeup latency < minimum constraint */
> + for (new_state = 0x0; new_state < PWRDM_MAX_PWRSTS; new_state++) {
> + if (min_latency == PM_QOS_DEV_LAT_DEFAULT_VALUE ||
> + pwrdm->wakeup_lat[new_state] <= min_latency)
Since min_latency is signed, this is a signed compare. In later patches
you've defined the UNSUP_STATE to be -1, which will always be <=
min_latency whn using a signed compare.
So, won't this always end up picking the first state marked as
UNSUP_STATE?
> + break;
> + }
Kevin
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