On 18/05/18 11:31, Ulf Hansson wrote:
The existing dev_pm_domain_attach() function, allows a single PM domain to
be attached per device. To be able to support devices that are partitioned
across multiple PM domains, let's introduce a new interface,
dev_pm_domain_attach_by_id().
The dev_pm_domain_attach_by_id() returns a new allocated struct device with
the corresponding attached PM domain. This enables for example a driver to
operate on the new device from a power management point of view. The driver
may then also benefit from using the received device, to set up so called
device-links towards its original device. Depending on the situation, these
links may then be dynamically changed.
The new interface is typically called by drivers during their probe phase,
in case they manages devices which uses multiple PM domains. If that is the
case, the driver also becomes responsible of managing the detaching of the
PM domains, which typically should be done at the remove phase. Detaching
is done by calling the existing dev_pm_domain_detach() function and for
each of the received devices from dev_pm_domain_attach_by_id().
Note, currently its only genpd that supports multiple PM domains per
device, but dev_pm_domain_attach_by_id() can easily by extended to cover
other PM domain types, if/when needed.
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
drivers/base/power/common.c | 33 ++++++++++++++++++++++++++++++++-
include/linux/pm_domain.h | 7 +++++++
2 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
index 7ae62b6..d3db974 100644
--- a/drivers/base/power/common.c
+++ b/drivers/base/power/common.c
@@ -117,13 +117,44 @@ int dev_pm_domain_attach(struct device *dev, bool power_on)
EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
/**
+ * dev_pm_domain_attach_by_id - Attach a device to one of its PM domains.
Isn't this more of a 'get'?
+ * @index: The index of the PM domain.
+ * @dev: Device to attach.
Isn't this just the device associated with the PM domain we are getting?
+ *
+ * As @dev may only be attached to a single PM domain, the backend PM domain
+ * provider should create a virtual device to attach instead. As attachment
+ * succeeds, the ->detach() callback in the struct dev_pm_domain should be
+ * assigned by the corresponding backend attach function.
+ *
+ * This function should typically be invoked from drivers during probe phase.
+ * Especially for those that manages devices which requires power management
+ * through more than one PM domain.
+ *
+ * Callers must ensure proper synchronization of this function with power
+ * management callbacks.
+ *
+ * Returns the virtual attached device in case successfully attached PM domain,
+ * NULL in case @dev don't need a PM domain, else a PTR_ERR().
Should this be 'NULL in the case where the @dev already has a power-domain'?
+ */
+struct device *dev_pm_domain_attach_by_id(struct device *dev,
+ unsigned int index)
+{
+ if (dev->pm_domain)
I wonder if this is worthy of a ...
if (WARN_ON(dev->pm_domain))
+ return NULL;
Don't we consider this an error case? I wonder why not return PTR_ERR
here as well? This would be consistent with dev_pm_domain_attach().
Cheers
Jon
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