lkml.org 
[lkml]   [2016]   [Sep]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH 2/3] PM / Domains: Add support for devices with multiple domains
From
Date

On 20/09/16 11:28, Jon Hunter wrote:
> Some devices may require more than one PM domain to operate and this is
> not currently by the PM domain framework. Furthermore, the current Linux
> 'device' structure only allows devices to be associated with a single PM
> domain and so cannot easily be associated with more than one. To allow
> devices to be associated with more than one PM domain, if multiple
> domains are defined for a given device (eg. via device-tree), then:
> 1. Create a new PM domain for this device. The name of the new PM domain
> created matches the device name for which it was created for.
> 2. Register the new PM domain as a sub-domain for all PM domains
> required by the device.
> 3. Attach the device to the new PM domain.
>
> By default the newly created PM domain is assumed to be in the 'off'
> state to ensure that any parent PM domains will be turned on if not
> already on when the new PM domain is turned on.
>
> When a device associated with more than one PM domain is detached,
> wait for any power-off work to complete, then remove the PM domain that
> was created for the device by calling pm_genpd_remove() (this also
> removes it as a child to any other PM domains) and free the memory
> for the PM domain.
>
> For devices using device-tree, devices that require multiple PM domains
> are detected by seeing if the 'power-domains' property has more than one
> entry defined.
>
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> ---
>
> Here is an example output from pm_genpd_summary following this change
> for the Tegra210 XHCI device:
>
> domain status slaves
> /device runtime status
> ----------------------------------------------------------------------
> 70090000.usb on
> /devices/platform/70090000.usb unsupported
> xusbc on 70090000.usb
> xusbb off-0
> xusba on 70090000.usb
>
> I am not sure if this is confusing to have a device and domain with the
> same name. So let me know if you have any thoughts!
>
>
> drivers/base/power/domain.c | 102 ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 88 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 382735949591..ee39824c03b3 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1826,7 +1826,7 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
> {
> struct generic_pm_domain *pd;
> unsigned int i;
> - int ret = 0;
> + int count, ret = 0;
>
> pd = genpd_lookup_dev(dev);
> if (!pd)
> @@ -1851,6 +1851,19 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>
> /* Check if PM domain can be powered off after removing this device. */
> genpd_queue_power_off_work(pd);
> +
> + count = of_count_phandle_with_args(dev->of_node, "power-domains",
> + "#power-domain-cells");
> + if (count > 1) {
> + cancel_work_sync(&pd->power_off_work);
> +
> + ret = pm_genpd_remove(pd);
> + if (ret < 0)
> + dev_err(dev, "failed to remove PM domain %s: %d\n",
> + pd->name, ret);
> +
> + kfree(pd);

I realise I am missing a return if pm_genpd_remove() returns a failure!
Will correct this.

Jon

--
nvpublic

\
 
 \ /
  Last update: 2016-09-20 19:55    [W:0.183 / U:0.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site