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[RFC,net-next,1/4] dt-bindings: dmaengine: bam_dma: Add remote power collapse mode

Message ID 20210719145317.79692-2-stephan@gerhold.net (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series net: wwan: Add Qualcomm BAM-DMUX WWAN network driver | expand

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Commit Message

Stephan Gerhold July 19, 2021, 2:53 p.m. UTC
In some configurations, the BAM DMA controller is set up by a remote
processor and the local processor can simply start making use of it
without setting up the BAM. This is already supported using the
"qcom,controlled-remotely" property.

However, for some reason another possible configuration is that the
remote processor is responsible for powering up the BAM, but we are
still responsible for initializing it (e.g. resetting it etc). Add
a "qcom,remote-power-collapse" property to describe that configuration.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
NOTE: This is *not* a compile-time requirement for the BAM-DMUX driver
      so this could also go through the dmaengine tree.

Also note that there is an ongoing effort to convert these bindings
to DT schema but sadly there were not any updates for a while. :/
https://lore.kernel.org/linux-arm-msm/20210519143700.27392-2-bhupesh.sharma@linaro.org/
---
 Documentation/devicetree/bindings/dma/qcom_bam_dma.txt | 2 ++
 1 file changed, 2 insertions(+)

Comments

Rob Herring (Arm) July 29, 2021, 7:36 p.m. UTC | #1
On Mon, Jul 19, 2021 at 04:53:14PM +0200, Stephan Gerhold wrote:
> In some configurations, the BAM DMA controller is set up by a remote
> processor and the local processor can simply start making use of it
> without setting up the BAM. This is already supported using the
> "qcom,controlled-remotely" property.
> 
> However, for some reason another possible configuration is that the
> remote processor is responsible for powering up the BAM, but we are
> still responsible for initializing it (e.g. resetting it etc). Add
> a "qcom,remote-power-collapse" property to describe that configuration.
> 
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> ---
> NOTE: This is *not* a compile-time requirement for the BAM-DMUX driver
>       so this could also go through the dmaengine tree.
> 
> Also note that there is an ongoing effort to convert these bindings
> to DT schema but sadly there were not any updates for a while. :/
> https://lore.kernel.org/linux-arm-msm/20210519143700.27392-2-bhupesh.sharma@linaro.org/
> ---
>  Documentation/devicetree/bindings/dma/qcom_bam_dma.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> index cf5b9e44432c..362a4f0905a8 100644
> --- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> +++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> @@ -15,6 +15,8 @@ Required properties:
>    the secure world.
>  - qcom,controlled-remotely : optional, indicates that the bam is controlled by
>    remote proccessor i.e. execution environment.
> +- qcom,remote-power-collapse : optional, indicates that the bam is powered up by
> +  a remote processor but must be initialized by the local processor.

Wouldn't 'qcom,remote-power' or 'qcom,remote-powered' be sufficient? I 
don't understand what 'collapse' means here. Doesn't sound good though.

Rob
Stephan Gerhold July 29, 2021, 7:50 p.m. UTC | #2
On Thu, Jul 29, 2021 at 01:36:31PM -0600, Rob Herring wrote:
> On Mon, Jul 19, 2021 at 04:53:14PM +0200, Stephan Gerhold wrote:
> > In some configurations, the BAM DMA controller is set up by a remote
> > processor and the local processor can simply start making use of it
> > without setting up the BAM. This is already supported using the
> > "qcom,controlled-remotely" property.
> > 
> > However, for some reason another possible configuration is that the
> > remote processor is responsible for powering up the BAM, but we are
> > still responsible for initializing it (e.g. resetting it etc). Add
> > a "qcom,remote-power-collapse" property to describe that configuration.
> > 
> > Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> > ---
> > NOTE: This is *not* a compile-time requirement for the BAM-DMUX driver
> >       so this could also go through the dmaengine tree.
> > 
> > Also note that there is an ongoing effort to convert these bindings
> > to DT schema but sadly there were not any updates for a while. :/
> > https://lore.kernel.org/linux-arm-msm/20210519143700.27392-2-bhupesh.sharma@linaro.org/
> > ---
> >  Documentation/devicetree/bindings/dma/qcom_bam_dma.txt | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> > index cf5b9e44432c..362a4f0905a8 100644
> > --- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> > +++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> > @@ -15,6 +15,8 @@ Required properties:
> >    the secure world.
> >  - qcom,controlled-remotely : optional, indicates that the bam is controlled by
> >    remote proccessor i.e. execution environment.
> > +- qcom,remote-power-collapse : optional, indicates that the bam is powered up by
> > +  a remote processor but must be initialized by the local processor.
> 
> Wouldn't 'qcom,remote-power' or 'qcom,remote-powered' be sufficient? I 
> don't understand what 'collapse' means here. Doesn't sound good though.
> 

Yeah I can't think of any significant meaning of the "collapse" part
for the bindings, I probably just picked it up somewhere while trying to
find some information about how the BAM DMUX setup works. :)

Just one question, would you prefer "qcom,remote-powered" or rather
"qcom,powered-remotely" for consistency with the existing
"qcom,controlled-remotely"? Both sounds fine to me.

Thanks!
Stephan
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
index cf5b9e44432c..362a4f0905a8 100644
--- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
+++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
@@ -15,6 +15,8 @@  Required properties:
   the secure world.
 - qcom,controlled-remotely : optional, indicates that the bam is controlled by
   remote proccessor i.e. execution environment.
+- qcom,remote-power-collapse : optional, indicates that the bam is powered up by
+  a remote processor but must be initialized by the local processor.
 - num-channels : optional, indicates supported number of DMA channels in a
   remotely controlled bam.
 - qcom,num-ees : optional, indicates supported number of Execution Environments