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

Rafael J. Wysocki
2018-01-11T22:53:15Z

On Tue, Jan 9, 2018 at 11:01 AM, Vivek Gautam
<vivek.gautam@codeaurora.org> 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@codeaurora.org>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Please feel free to route this along with the rest of the series.

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
>