[PATCH RFC 01/27] PM / Domains: core changes for multiple states
Ulf Hansson
ulf.hansson at linaro.org
Wed Dec 9 05:58:18 PST 2015
On 17 November 2015 at 23:37, Lina Iyer <lina.iyer at linaro.org> wrote:
> From: Axel Haslam <ahaslam+renesas at baylibre.com>
>
> From: Axel Haslam <ahaslam at baylibre.com>
>
> Add the core changes to be able to declare multiple states.
> When trying to set a power domain to off, genpd will be able to choose
> from an array of states declared by the platform. The power on and off
> latencies are now tied to a state.
I would like to get an answer to *why* we need this.
For example, we should mention that some HWs supports these multiple
states - at least.
>
> States should be declared in ascending order from shallowest to deepest,
I guess *should* isn't good enough. Perhaps *shall* is better?
> deepest meaning the state which takes longer to enter and exit.
>
> the power_off and power_on function can use the 'state_idx' field of the
> generic_pm_domain structure, to distinguish between the different states
> and act accordingly.
This needs some more explanation.
First, please use the wording of "callbacks", like ->power_on() to
better describe what function you are talking about.
Second, what is "state_idx"? What's does it really tell the SOC PM
domain driver here?
>
> Example:
>
> static int pd1_power_on(struct generic_pm_domain *domain)
> {
> /* domain->state_idx = state the domain is coming from */
> }
>
> static int pd1_power_off(struct generic_pm_domain *domain)
> {
> /* domain->state_idx = desired powered off state */
> }
>
> const struct genpd_power_state pd_states[] = {
> {
> .name = "RET",
> .power_on_latency_ns = ON_LATENCY_FAST,
> .power_off_latency_ns = OFF_LATENCY_FAST,
> },
> {
> .name = "DEEP_RET",
> .power_on_latency_ns = ON_LATENCY_MED,
> .power_off_latency_ns = OFF_LATENCY_MED,
> },
> {
> .name = "OFF",
> .power_on_latency_ns = ON_LATENCY_SLOW,
> .power_off_latency_ns = OFF_LATENCY_SLOW,
> }
> };
>
> struct generic_pm_domain pd1 = {
> .name = "PD1",
> .power_on = pd1_power_on,
> .power_off = pd1_power_off,
> [...]
> };
>
> int xxx_init_pm_domain(){
>
> pd1->state = copy_of(pd_states);
> pd1->state_count = ARRAY_SIZE(pd_states);
> pm_genpd_init(pd1, true);
>
> }
Well, even if the above describes this quite good, I think it better
belongs in the Documentation rather than in the change log.
Can we try to the improve the text in the change-log instead?
>
> Signed-off-by: Axel Haslam <ahaslam+renesas at baylibre.com>
> Signed-off-by: Lina Iyer <lina.iyer at linaro.org>
> [Lina: Modified genpd state initialization and remove use of
> save_state_latency_ns in genpd timing data]
>
> Signed-off-by: Lina Iyer <lina.iyer at linaro.org>
> ---
> drivers/base/power/domain.c | 136 +++++++++++++++++++++++++++++++++--
> drivers/base/power/domain_governor.c | 13 +++-
> include/linux/pm_domain.h | 10 +++
> 3 files changed, 151 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index e03b1ad..3242854 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -34,6 +34,12 @@
> __ret; \
> })
>
> +#define GENPD_MAX_NAME_SIZE 20
> +
> +static int pm_genpd_alloc_states_names(struct generic_pm_domain *genpd,
Please avoid forward declarations.
Also, we have just got rid of all *name* based genpd API/functions. I
don't want us to start adding another.
Or perhaps it's just the name of the function that I don't like!? :-)
> + const struct genpd_power_state *st,
> + unsigned int st_count);
> +
> static LIST_HEAD(gpd_list);
> static DEFINE_MUTEX(gpd_list_lock);
>
> @@ -102,6 +108,7 @@ static void genpd_sd_counter_inc(struct generic_pm_domain *genpd)
>
> static int genpd_power_on(struct generic_pm_domain *genpd, bool timed)
> {
> + unsigned int state_idx = genpd->state_idx;
> ktime_t time_start;
> s64 elapsed_ns;
> int ret;
> @@ -118,10 +125,10 @@ static int genpd_power_on(struct generic_pm_domain *genpd, bool timed)
> return ret;
>
> elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
> - if (elapsed_ns <= genpd->power_on_latency_ns)
> + if (elapsed_ns <= genpd->states[state_idx].power_on_latency_ns)
> return ret;
>
> - genpd->power_on_latency_ns = elapsed_ns;
> + genpd->states[state_idx].power_on_latency_ns = elapsed_ns;
> genpd->max_off_time_changed = true;
> pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
> genpd->name, "on", elapsed_ns);
> @@ -131,6 +138,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, bool timed)
>
> static int genpd_power_off(struct generic_pm_domain *genpd, bool timed)
> {
> + unsigned int state_idx = genpd->state_idx;
> ktime_t time_start;
> s64 elapsed_ns;
> int ret;
> @@ -147,10 +155,10 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool timed)
> return ret;
>
> elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
> - if (elapsed_ns <= genpd->power_off_latency_ns)
> + if (elapsed_ns <= genpd->states[state_idx].power_off_latency_ns)
> return ret;
>
> - genpd->power_off_latency_ns = elapsed_ns;
> + genpd->states[state_idx].power_off_latency_ns = elapsed_ns;
> genpd->max_off_time_changed = true;
> pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
> genpd->name, "off", elapsed_ns);
> @@ -582,6 +590,8 @@ static void pm_genpd_sync_poweroff(struct generic_pm_domain *genpd,
> || atomic_read(&genpd->sd_count) > 0)
> return;
>
> + /* Choose the deepest state when suspending */
> + genpd->state_idx = genpd->state_count - 1;
> genpd_power_off(genpd, timed);
>
> genpd->status = GPD_STATE_POWER_OFF;
> @@ -1205,6 +1215,61 @@ static void genpd_free_dev_data(struct device *dev,
> dev_pm_put_subsys_data(dev);
> }
>
> +static int genpd_alloc_states_data(struct generic_pm_domain *genpd,
In this patch I would rather just add *one* new "alloc" function and
name it like below.
static int genpd_alloc_default_state(struct generic_pm_domain *genpd)
I assume the name I suggest for it, indicates what it needs to do and
*not* needs to do.
> + const struct genpd_power_state *st,
> + unsigned int st_count)
> +{
> + int ret = 0;
> + unsigned int i;
> +
> + if (IS_ERR_OR_NULL(genpd)) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + if (!st || (st_count < 1)) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + /* Allocate the local memory to keep the states for this genpd */
> + genpd->states = kcalloc(st_count, sizeof(*st), GFP_KERNEL);
> + if (!genpd->states) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + for (i = 0; i < st_count; i++) {
> + genpd->states[i].power_on_latency_ns =
> + st[i].power_on_latency_ns;
> + genpd->states[i].power_off_latency_ns =
> + st[i].power_off_latency_ns;
> + }
> +
> + /*
> + * Copy the latency values To keep compatibility with
> + * platforms that are not converted to use the multiple states.
> + * This will be removed once all platforms are converted to use
> + * multiple states. note that non converted platforms will use the
> + * default single off state.
> + */
> + if (genpd->power_on_latency_ns != 0)
> + genpd->states[0].power_on_latency_ns =
> + genpd->power_on_latency_ns;
> +
> + if (genpd->power_off_latency_ns != 0)
> + genpd->states[0].power_off_latency_ns =
> + genpd->power_off_latency_ns;
> +
> + genpd->state_count = st_count;
> +
> + /* to save memory, Name allocation will happen if debug is enabled */
Urgh. :-)
I instead suggest we skip the entire "name" attribute" and just use
the state_idx to provide the same information.
For sure at this point, this information won't be interpreted by
"anybody". Reading an integer value instead of string, shouldn't be
that difficult to understand.
Future wise, if we see that it could be beneficial to add the "name"
attribute, we can do that then.
Removing the name attribute will also simplify this patch, quite much.
Can you please do that.
> + pm_genpd_alloc_states_names(genpd, st, st_count);
> +
> +err:
> + return ret;
> +}
> +
> /**
> * __pm_genpd_add_device - Add a device to an I/O PM domain.
> * @genpd: PM domain to add the device to.
> @@ -1459,6 +1524,15 @@ static int pm_genpd_default_restore_state(struct device *dev)
> void pm_genpd_init(struct generic_pm_domain *genpd,
> struct dev_power_governor *gov, bool is_off)
> {
> + int ret;
> + static const struct genpd_power_state genpd_default_off[] = {
> + {
> + .name = "OFF",
> + .power_off_latency_ns = 0,
> + .power_on_latency_ns = 0,
> + },
> + };
I suggest you remove this and instead handle that within
genpd_alloc_default_state().
> +
> if (IS_ERR_OR_NULL(genpd))
> return;
>
> @@ -1503,6 +1577,19 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
> genpd->dev_ops.start = pm_clk_resume;
> }
>
> + /*
> + * Allocate the default state if genpd states
> + * are not already defined.
> + */
> + if (!genpd->state_count) {
> + ret = genpd_alloc_states_data(genpd, genpd_default_off, 1);
Call the new "genpd_alloc_default_state()" instead.
> + if (ret)
> + return;
> + }
> +
> + /* Assume the deepest state on init*/
> + genpd->state_idx = genpd->state_count - 1;
When the PM domain is powered on, in other words the genpd->status ==
GPD_STATE_ACTIVE, I guess this value doesn't matter much.
Although, what if the PM domain is powered off, don't you need to
respect the value that might have been assigned by the SoC PM domain
driver? Else you may at the next power on, indicate that you are
coming from a state that's not the correct one.
Perhaps, you should only set genpd->state_idx = 0, from
genpd_alloc_default_state() and in the other case leave the value as
is?
> +
> mutex_lock(&gpd_list_lock);
> list_add(&genpd->gpd_list_node, &gpd_list);
> mutex_unlock(&gpd_list_lock);
> @@ -1822,6 +1909,33 @@ EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
> #include <linux/kobject.h>
> static struct dentry *pm_genpd_debugfs_dir;
>
> +static int pm_genpd_alloc_states_names(struct generic_pm_domain *genpd,
> + const struct genpd_power_state *st,
> + unsigned int st_count)
> +{
> + unsigned int i;
> +
> + if (IS_ERR_OR_NULL(genpd))
> + return -EINVAL;
> +
> + if (genpd->state_count != st_count) {
> + pr_err("Invalid allocated state count\n");
> + return -EINVAL;
> + }
> +
> + for (i = 0; i < st_count; i++) {
> + genpd->states[i].name = kstrndup(st[i].name,
> + GENPD_MAX_NAME_SIZE, GFP_KERNEL);
> + if (!genpd->states[i].name) {
> + pr_err("%s Failed to allocate state %d name.\n",
> + genpd->name, i);
> + return -ENOMEM;
> + }
> + }
> +
> + return 0;
> +}
> +
> /*
> * TODO: This function is a slightly modified version of rtpm_status_show
> * from sysfs.c, so generalize it.
> @@ -1855,6 +1969,7 @@ static int pm_genpd_summary_one(struct seq_file *s,
> [GPD_STATE_ACTIVE] = "on",
> [GPD_STATE_POWER_OFF] = "off"
> };
> + unsigned int state_idx = genpd->state_idx;
> struct pm_domain_data *pm_data;
> const char *kobj_path;
> struct gpd_link *link;
> @@ -1866,7 +1981,11 @@ static int pm_genpd_summary_one(struct seq_file *s,
>
> if (WARN_ON(genpd->status >= ARRAY_SIZE(status_lookup)))
> goto exit;
> - seq_printf(s, "%-30s %-15s ", genpd->name, status_lookup[genpd->status]);
> +
> + seq_printf(s, "%-30s %-15s ", genpd->name,
> + (genpd->status == GPD_STATE_POWER_OFF) ?
> + genpd->states[state_idx].name :
> + status_lookup[genpd->status]);
>
> /*
> * Modifications on the list require holding locks on both
> @@ -1954,4 +2073,11 @@ static void __exit pm_genpd_debug_exit(void)
> debugfs_remove_recursive(pm_genpd_debugfs_dir);
> }
> __exitcall(pm_genpd_debug_exit);
> +#else
> +static inline int pm_genpd_alloc_states_names(struct generic_pm_domain *genpd,
> + const struct genpd_power_state *st,
> + unsigned int st_count)
> +{
> + return 0;
> +}
> #endif /* CONFIG_PM_ADVANCED_DEBUG */
> diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
> index e60dd12..b4984f5 100644
> --- a/drivers/base/power/domain_governor.c
> +++ b/drivers/base/power/domain_governor.c
> @@ -125,8 +125,12 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
> return genpd->cached_power_down_ok;
> }
>
> - off_on_time_ns = genpd->power_off_latency_ns +
> - genpd->power_on_latency_ns;
> + /*
> + * Use the only available state, until multiple state support is added
> + * to the governor.
> + */
So you want to delay this step into a later patch. I am fine with
that, but you need to state that in the change-log.
Perhaps it's better to say that we will always try with the
shallowest/deepest off state, and just ignore the other states in this
phase?
> + off_on_time_ns = genpd->states[0].power_off_latency_ns +
> + genpd->states[0].power_on_latency_ns;
If you think my above idea seems reasonable, that should change the above to:
off_on_time_ns = genpd->states[genpd->state_count - 1].power_off_latency_ns +
genpd->states[genpd->state_count - 1].power_on_latency_ns;
>
> min_off_time_ns = -1;
> /*
> @@ -203,8 +207,11 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
> * The difference between the computed minimum subdomain or device off
> * time and the time needed to turn the domain on is the maximum
> * theoretical time this domain can spend in the "off" state.
> + * Use the only available state, until multiple state support is added
> + * to the governor.
> */
> - genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
> + genpd->max_off_time_ns = min_off_time_ns -
> + genpd->states[0].power_on_latency_ns;
Ditto.
> return true;
> }
>
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index ba4ced3..11763cf 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -37,6 +37,12 @@ struct gpd_dev_ops {
> bool (*active_wakeup)(struct device *dev);
> };
>
> +struct genpd_power_state {
> + char *name;
As stated, suggest to remove "name".
> + s64 power_off_latency_ns;
> + s64 power_on_latency_ns;
> +};
> +
> struct generic_pm_domain {
> struct dev_pm_domain domain; /* PM domain operations */
> struct list_head gpd_list_node; /* Node in the global PM domains list */
> @@ -66,6 +72,10 @@ struct generic_pm_domain {
> void (*detach_dev)(struct generic_pm_domain *domain,
> struct device *dev);
> unsigned int flags; /* Bit field of configs for genpd */
> + struct genpd_power_state *states;
> + unsigned int state_count; /* number of states */
> + unsigned int state_idx; /* state that genpd will go to when off */
> +
> };
>
> static inline struct generic_pm_domain *pd_to_genpd(struct dev_pm_domain *pd)
> --
> 2.1.4
>
Kind regards
Uffe
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