* 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:
https://lore.kernel.org/linux-remoteproc/[email protected]/
2. DTS changes (v1):
https://lore.kernel.org/linux-devicetree/[email protected]/
This serie does not depend on any serie, but all of them are necessary
to enable the feature in the end.
* Changelog *
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.
Kind regards,
Dylan Van Assche
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 | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
--
2.39.2
Use fastrpc_remote_heap_alloc to allocate from the FastRPC device
instead of the Compute Bank when the session ID is 0. This ensures
that the allocation is inside the coherent DMA pool which is already
accessible to the DSP. This is necessary to support FastRPC devices
which do not have dedicated Compute Banks such as the SLPI on the SDM845.
The latter uses an allocated CMA region instead of FastRPC Compute Banks.
Signed-off-by: Dylan Van Assche <[email protected]>
---
drivers/misc/fastrpc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index caf2ae556956..b7ddf6b90022 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -939,7 +939,10 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
ctx->msg_sz = pkt_size;
- err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
+ if (ctx->fl->sctx->sid)
+ err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
+ else
+ err = fastrpc_remote_heap_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
if (err)
return err;
--
2.39.2
On 27/03/2023 19:42, Dylan Van Assche wrote:
> Use fastrpc_remote_heap_alloc to allocate from the FastRPC device
> instead of the Compute Bank when the session ID is 0. This ensures
> that the allocation is inside the coherent DMA pool which is already
> accessible to the DSP. This is necessary to support FastRPC devices
> which do not have dedicated Compute Banks such as the SLPI on the SDM845.
> The latter uses an allocated CMA region instead of FastRPC Compute Banks.
>
> Signed-off-by: Dylan Van Assche <[email protected]>
Reviewed-by: Caleb Connolly <[email protected]>
> ---
> drivers/misc/fastrpc.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index caf2ae556956..b7ddf6b90022 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -939,7 +939,10 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>
> ctx->msg_sz = pkt_size;
>
> - err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
> + if (ctx->fl->sctx->sid)
> + err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
> + else
> + err = fastrpc_remote_heap_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
> if (err)
> return err;
>
> --
> 2.39.2
>
--
Kind Regards,
Caleb