| Message ID | 20180530105059.21409-1-johan@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Wed, May 30, 2018 at 5:50 AM, Johan Hovold <johan@kernel.org> wrote: > Add support for controller runtime power management to serdev core. This > is needed to allow slave drivers to manage the runtime PM state of the > underlying serial controller when its driver, in turn, implements more > aggressive runtime power management (e.g. using autosuspend). > > For some applications, for example, where loss off initial data after a > remote-wakeup event is acceptable or where rx is not used at all, > aggressive serial controller runtime PM may be used without further > involvement of the slave driver. But when this is not the case, the > slave driver must be able to indicate when incoming data is expected in > order to avoid data loss. > > To facilitate the common case, where the serial controller power state > is active whenever the port is open (which is the case with just about > every serial driver), and where data loss is not acceptable and cannot > even be prevented by explicit controller runtime power management, an > RPM reference is taken in serdev open and put again at close. This > reference can later be balanced by any serdev driver which wants and/or > can handle aggressive controller runtime PM. > > Note that the .ignore_children flag is set for the serdev controller to > allow the underlying hardware to idle when no I/O is expected, regardless > of the slave device RPM state. > > Acked-by: Tony Lindgren <tony@atomide.com> > Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk> > Signed-off-by: Johan Hovold <johan@kernel.org> > --- > > Hi Rob and Greg, > > This is a resend of the serdev controller runtime PM patch, which you > haven't commented on yet (possibly due to the following extensive > discussions on how to generalise the aggressive OMAP serial runtime PM > implementation). > > This patch works with what we have today, regardless of how we end up > configuring the serial controller (active) runtime PM behaviour > (currently done through sysfs for OMAP), which is a separate issue. > > No changes in this resend, besides me adding Tony's and Sebastian's ack > and reviewed-by tags and dropping the second patch which only served as > an example of how to use this in a serdev driver. Acked-by: Rob Herring <robh@kernel.org> Rob
diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c index df93b727e984..e5e84303faca 100644 --- a/drivers/tty/serdev/core.c +++ b/drivers/tty/serdev/core.c @@ -13,6 +13,7 @@ #include <linux/module.h> #include <linux/of.h> #include <linux/of_device.h> +#include <linux/pm_runtime.h> #include <linux/serdev.h> #include <linux/slab.h> @@ -143,11 +144,28 @@ EXPORT_SYMBOL_GPL(serdev_device_remove); int serdev_device_open(struct serdev_device *serdev) { struct serdev_controller *ctrl = serdev->ctrl; + int ret; if (!ctrl || !ctrl->ops->open) return -EINVAL; - return ctrl->ops->open(ctrl); + ret = ctrl->ops->open(ctrl); + if (ret) + return ret; + + ret = pm_runtime_get_sync(&ctrl->dev); + if (ret < 0) { + pm_runtime_put_noidle(&ctrl->dev); + goto err_close; + } + + return 0; + +err_close: + if (ctrl->ops->close) + ctrl->ops->close(ctrl); + + return ret; } EXPORT_SYMBOL_GPL(serdev_device_open); @@ -158,6 +176,8 @@ void serdev_device_close(struct serdev_device *serdev) if (!ctrl || !ctrl->ops->close) return; + pm_runtime_put(&ctrl->dev); + ctrl->ops->close(ctrl); } EXPORT_SYMBOL_GPL(serdev_device_close); @@ -416,6 +436,9 @@ struct serdev_controller *serdev_controller_alloc(struct device *parent, dev_set_name(&ctrl->dev, "serial%d", id); + pm_runtime_no_callbacks(&ctrl->dev); + pm_suspend_ignore_children(&ctrl->dev, true); + dev_dbg(&ctrl->dev, "allocated controller 0x%p id %d\n", ctrl, id); return ctrl; @@ -547,20 +570,23 @@ int serdev_controller_add(struct serdev_controller *ctrl) if (ret) return ret; + pm_runtime_enable(&ctrl->dev); + ret_of = of_serdev_register_devices(ctrl); ret_acpi = acpi_serdev_register_devices(ctrl); if (ret_of && ret_acpi) { dev_dbg(&ctrl->dev, "no devices registered: of:%d acpi:%d\n", ret_of, ret_acpi); ret = -ENODEV; - goto out_dev_del; + goto err_rpm_disable; } dev_dbg(&ctrl->dev, "serdev%d registered: dev:%p\n", ctrl->nr, &ctrl->dev); return 0; -out_dev_del: +err_rpm_disable: + pm_runtime_disable(&ctrl->dev); device_del(&ctrl->dev); return ret; }; @@ -591,6 +617,7 @@ void serdev_controller_remove(struct serdev_controller *ctrl) dummy = device_for_each_child(&ctrl->dev, NULL, serdev_remove_device); + pm_runtime_disable(&ctrl->dev); device_del(&ctrl->dev); } EXPORT_SYMBOL_GPL(serdev_controller_remove);