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/ (local)
---
 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.