[v4,0/2] misc: fastrpc: FastRPC reserved memory assignment for SDM845 SLPI

Message

Dylan Van Assche May 11, 2023, 2:11 p.m. UTC

* About *

The Qualcomm SDM845 SoC has a separate SLPI (Sensor Low Power Island)
DSP for sensors connected to the SoC which is responsible for exposing
sensors to userspace, power saving, and other features. 
While sensors are connected to GPIOs of the SoC, they cannot be used
because the hypervisor blocks direct access to the sensors, thus the 
DSP must be used to access any sensor on this SoC. The SLPI DSP uses a
GLink edge (dsps) to communicate with the host and has a FastRPC interface
to load files from the host filesystem such as sensor configuration files.
The FastRPC interface does not use regular FastRPC Compute Banks
but instead uses an allocated CMA region through which communication happens.

* Changes *

This patchseries add support to the FastRPC for assigning a coherent memory
region to a DSP via the hypervisor with the correct permissions.
This is necessary to support the SLPI found in the Qualcomm SDM845 SoC which
does not have dedicated FastRPC Compute Banks, in contrast to newer SoCs,
but uses a memory region instead when allocating buffers.

* Related patches *

1. Remoteproc changes to support the SLPI DSP in SDM845 (v3), needs to be applied:
https://lore.kernel.org/linux-remoteproc/[e-mail]
2. DTS changes (v5), already applied:
https://lore.kernel.org/linux-devicetree/[e-mail]

This serie does not depend on any serie, but all of them are necessary
to enable the feature in the end.

* Changelog *

Changes in v4:
- Fixed possible memory leak when driver encounters an error during probing.

Changes in v3:
- Dropped debug prints.
- Added Reviewed-By tags from v2.

Changes in v2:

- Removed double blank lines
- Dropped dt-bindings property as it is not needed for driver behavior
- Add additional patch to allocate buffers via CMA memory for DSPs
  without dedicated FastRPC Compute Banks.

Dylan Van Assche (2):
  misc: fastrpc: support complete DMA pool access to the DSP
  misc: fastrpc: use coherent pool for untranslated Compute Banks

 drivers/misc/fastrpc.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)