[PATCH 08/10] PM / Domains: Add support for removing PM domains
Jon Hunter
jonathanh at nvidia.com
Fri Sep 9 08:17:33 PDT 2016
On 09/09/16 14:54, Jon Hunter wrote:
> On 08/09/16 12:49, Ulf Hansson wrote:
>> On 16 August 2016 at 11:49, Jon Hunter <jonathanh at nvidia.com> wrote:
>>> The genpd framework allows users to add PM domains via the pm_genpd_init()
>>> function, however, there is no corresponding function to remove a PM
>>> domain. For most devices this may be fine as the PM domains are never
>>> removed, however, for devices that wish to populate the PM domains from
>>> within a driver, having the ability to remove a PM domain if the probing
>>> of the device fails or the driver is unloaded is necessary.
>>>
>>> Add the function pm_genpd_remove() to remove a PM domain by referencing
>>> it's generic_pm_domain structure.
>>>
>>> PM domains can only be removed if they are not a parent domain to
>>> another PM domain and have no devices associated with them.
>>
>> I think we should also check if the there's is a provider registered
>> for the genpd, as it should also prevent the genpd from being removed.
>> Right?
>
> Yes I would agree. I had thought that after patch #4 of this series that
> only the provider itself would be able to call this. However, we should
> probably still verify that the provider has correctly remove itself.
So now I have the following. I am still not 100% happy. I cannot clear
the ->provider when calling of_genpd_del_provider() and so I cannot use
this to verify if the provider is present and so I need to check the
list of providers and it gets a bit messy. I have been wracking my
brains to find a better alternative (including a single function to
remove the provider and domains at once but there are issues with that
as well).
I think that long term it may make sense to reference the providers
exclusively by the fwnode_handle and make the list of provider non-DT
specific. I could do it now, but it would increase the series.
Cheers
Jon
---
drivers/base/power/domain.c | 89 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/pm_domain.h | 5 +++
2 files changed, 94 insertions(+)
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 82f87038f108..57c64fc1a164 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -39,6 +39,8 @@
static LIST_HEAD(gpd_list);
static DEFINE_MUTEX(gpd_list_lock);
+static bool genpd_provider_present(struct device_node *np);
+
/*
* Get the generic PM domain for a particular struct device.
* This validates the struct device pointer, the PM domain pointer,
@@ -1356,6 +1358,68 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
}
EXPORT_SYMBOL_GPL(pm_genpd_init);
+static int genpd_remove(struct generic_pm_domain *genpd)
+{
+ struct gpd_link *l, *link;
+
+ if (IS_ERR_OR_NULL(genpd))
+ return -EINVAL;
+
+ mutex_lock(&genpd->lock);
+
+ if (is_of_node(genpd->provider)) {
+ if (genpd_provider_present(to_of_node(genpd->provider))) {
+ mutex_unlock(&genpd->lock);
+ pr_err("Provider present, unable to remove %s\n",
+ genpd->name);
+ return -EBUSY;
+ }
+ }
+
+ if (!list_empty(&genpd->master_links) || genpd->device_count) {
+ mutex_unlock(&genpd->lock);
+ pr_err("%s: unable to remove %s\n", __func__, genpd->name);
+ return -EBUSY;
+ }
+
+ list_for_each_entry_safe(link, l, &genpd->slave_links, slave_node) {
+ list_del(&link->master_node);
+ list_del(&link->slave_node);
+ kfree(link);
+ }
+
+ list_del(&genpd->gpd_list_node);
+ mutex_unlock(&genpd->lock);
+ cancel_work_sync(&genpd->power_off_work);
+ pr_debug("%s: removed %s\n", __func__, genpd->name);
+
+ return 0;
+}
+
+/**
+ * pm_genpd_remove - Remove a generic I/O PM domain
+ * @genpd: Pointer to PM domain that is to be removed.
+ *
+ * To remove the PM domain, this function:
+ * - Removes the PM domain as a subdomain to any parent domains,
+ * if it was added.
+ * - Removes the PM domain from the list of registered PM domains.
+ *
+ * The PM domain will only be removed, if it is not a parent to any
+ * other PM domain and has no devices associated with it.
+ */
+int pm_genpd_remove(struct generic_pm_domain *genpd)
+{
+ int ret;
+
+ mutex_lock(&gpd_list_lock);
+ ret = genpd_remove(genpd);
+ mutex_unlock(&gpd_list_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(pm_genpd_remove);
+
#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
typedef struct generic_pm_domain *(*genpd_xlate_t)(struct of_phandle_args *args,
@@ -1563,6 +1627,26 @@ void of_genpd_del_provider(struct device_node *np)
EXPORT_SYMBOL_GPL(of_genpd_del_provider);
/**
+ * genpd_provider_present() - Verify if a PM domain provider is present
+ * @np: Device node pointer associated with the PM domain provider
+ */
+static bool genpd_provider_present(struct device_node *np)
+{
+ struct of_genpd_provider *cp;
+
+ mutex_lock(&of_genpd_mutex);
+ list_for_each_entry(cp, &of_genpd_providers, link) {
+ if (cp->node == np) {
+ mutex_unlock(&of_genpd_mutex);
+ return true;
+ }
+ }
+ mutex_unlock(&of_genpd_mutex);
+
+ return false;
+}
+
+/**
* genpd_get_from_provider() - Look-up PM domain
* @genpdspec: OF phandle args to use for look-up
*
@@ -1798,6 +1882,11 @@ out:
return ret ? -EPROBE_DEFER : 0;
}
EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
+#else
+static bool genpd_provider_present(struct device_node *np)
+{
+ return false;
+}
#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index e71764ac7248..4aa285e44eb0 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -129,6 +129,7 @@ extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
struct generic_pm_domain *target);
extern int pm_genpd_init(struct generic_pm_domain *genpd,
struct dev_power_governor *gov, bool is_off);
+extern int pm_genpd_remove(struct generic_pm_domain *genpd);
extern struct dev_power_governor simple_qos_governor;
extern struct dev_power_governor pm_domain_always_on_gov;
@@ -164,6 +165,10 @@ static inline int pm_genpd_init(struct generic_pm_domain *genpd,
{
return -ENOSYS;
}
+static inline int pm_genpd_remove(struct generic_pm_domain *genpd)
+{
+ return -ENOTSUPP;
+}
#endif
static inline int pm_genpd_add_device(struct generic_pm_domain *genpd,
--
2.1.4
--
nvpublic
More information about the linux-arm-kernel
mailing list