Messages in this thread | | | Subject | Re: [PATCH 8/9] PM / Domains: Add support for multi PM domains per device to genpd | From | Jon Hunter <> | Date | Tue, 22 May 2018 21:55:15 +0100 |
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On 22/05/18 15:47, Ulf Hansson wrote: > [...] > >>> >>> +/** >>> + * genpd_dev_pm_attach_by_id() - Attach a device to one of its PM domain. >>> + * @dev: Device to attach. >>> + * @index: The index of the PM domain. >>> + * >>> + * Parse device's OF node to find a PM domain specifier at the provided @index. >>> + * If such is found, allocates a new device and attaches it to retrieved >>> + * pm_domain ops. >>> + * >>> + * Returns the allocated device if successfully attached PM domain, NULL when >>> + * the device don't need a PM domain or have a single PM domain, else PTR_ERR() >>> + * in case of failures. Note that if a power-domain exists for the device, but >>> + * cannot be found or turned on, then return PTR_ERR(-EPROBE_DEFER) to ensure >>> + * that the device is not probed and to re-try again later. >>> + */ >>> +struct device *genpd_dev_pm_attach_by_id(struct device *dev, >>> + unsigned int index) >>> +{ >>> + struct device *genpd_dev; >>> + int num_domains; >>> + int ret; >>> + >>> + if (!dev->of_node) >>> + return NULL; >>> + >>> + /* Deal only with devices using multiple PM domains. */ >>> + num_domains = of_count_phandle_with_args(dev->of_node, "power-domains", >>> + "#power-domain-cells"); >>> + if (num_domains < 2 || index >= num_domains) >>> + return NULL; >>> + >>> + /* Allocate and register device on the genpd bus. */ >>> + genpd_dev = kzalloc(sizeof(*genpd_dev), GFP_KERNEL); >>> + if (!genpd_dev) >>> + return ERR_PTR(-ENOMEM); >>> + >>> + dev_set_name(genpd_dev, "genpd:%u:%s", index, dev_name(dev)); >>> + genpd_dev->bus = &genpd_bus_type; >>> + genpd_dev->release = genpd_release_dev; >>> + >>> + ret = device_register(genpd_dev); >>> + if (ret) { >>> + kfree(genpd_dev); >>> + return ERR_PTR(ret); >>> + } >>> + >>> + /* Try to attach the device to the PM domain at the specified index. */ >>> + ret = __genpd_dev_pm_attach(genpd_dev, dev->of_node, index); >>> + if (ret < 1) { >>> + device_unregister(genpd_dev); >>> + return ret ? ERR_PTR(ret) : NULL; >>> + } >>> + >>> + pm_runtime_set_active(genpd_dev); >>> + pm_runtime_enable(genpd_dev); >>> + >>> + return genpd_dev; >>> +} >>> +EXPORT_SYMBOL_GPL(genpd_dev_pm_attach_by_id); >> >> Thanks for sending this. Believe it or not this has still been on my to-do list >> and so we definitely need a solution for Tegra. >> >> Looking at the above it appears that additional power-domains exposed as devices >> to the client device. So I assume that this means that the drivers for devices >> with multiple power-domains will need to call RPM APIs for each of these >> additional power-domains. Is that correct? > > They can, but should not! > > Instead, the driver shall use device_link_add() and device_link_del(), > dynamically, depending on what PM domain that their original device > needs for the current running use case. > > In that way, they keep existing runtime PM deployment, operating on > its original device.
OK, sounds good. Any reason why the linking cannot be handled by the above API? Is there a use-case where you would not want it linked?
Thanks Jon
-- nvpublic
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