Re: [PATCH v5 1/6] base: power: runtime: Export pm_runtime_get/put_suppliers

[Vivek Gautam]

On 01/12/2018 04:23 AM, Rafael J. Wysocki wrote:
> On Tue, Jan 9, 2018 at 11:01 AM, Vivek Gautam
> <vivek.gautam@xxxxxxxxxxxxxx> wrote:
> > The device link allows the pm framework to tie the supplier and
> > consumer. So, whenever the consumer is powered-on the supplier
> > is powered-on first.
> >
> > There are however cases in which the consumer wants to power-on
> > the supplier, but not itself.
> > E.g., A Graphics or multimedia driver wants to power-on the SMMU
> > to unmap a buffer and finish the TLB operations without powering
> > on itself. Some of these unmap requests are coming from the
> > user space when the controller itself is not powered-up, and it
> > can be huge penalty in terms of power and latency to power-up
> > the graphics/mm controllers.
> > There can be an argument that the supplier should handle this case
> > on its own and there should not be a need for the consumer to
> > power-on the supplier. But as discussed on the thread [1] about
> > ARM-SMMU runtime pm, we don't want to introduce runtime pm calls
> > in atomic path in arm_smmu_unmap.
> >
> > [1] https://patchwork.kernel.org/patch/9827825/
> >
> > Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Please feel free to route this along with the rest of the series.

Thanks Rafael.

regards
Vivek

> Thanks!
>
> > ---
> >
> >   * This is v2 of the patch [1]. Adding it to this patch series.
> >     [1] https://patchwork.kernel.org/patch/10102447/
> >
> >   drivers/base/power/runtime.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 6e89b51ea3d9..06a2a88fe866 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -1579,6 +1579,7 @@ void pm_runtime_get_suppliers(struct device *dev)
> >
> >          device_links_read_unlock(idx);
> >   }
> > +EXPORT_SYMBOL_GPL(pm_runtime_get_suppliers);
> >
> >   /**
> >    * pm_runtime_put_suppliers - Drop references to supplier devices.
> > @@ -1597,6 +1598,7 @@ void pm_runtime_put_suppliers(struct device *dev)
> >
> >          device_links_read_unlock(idx);
> >   }
> > +EXPORT_SYMBOL_GPL(pm_runtime_put_suppliers);
> >
> >   void pm_runtime_new_link(struct device *dev)
> >   {
> > --
> > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> > of Code Aurora Forum, hosted by The Linux Foundation
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