On 18/11/2022 11:45, Krzysztof Kozlowski wrote:
On 17/11/2022 10:47, Neil Armstrong wrote:
+
+properties:
+ compatible:
+ const: qcom,mpss-dsm-mem
Why do we need dedicated binding and compatible for it instead of using
memory-region phandle in the device?
So like rmtfs, this memory zone is shared between APPS and the MPSS subsystem.
Like rmtfs it makes no sense to link it to the MPSS PAS, since it's only a launcher,
it doesn't represent the MPSS subsystem.
This also does not represent a device. Memory region is not a device, so
this is as well not correct representation of hardware.
I never used the term device so far, but a shared memory region with a platform
specific process to share the region between subsystems.
In the PAS startup process, the resources are released from APPS once the MPSS subsystem
is running, which is not the case with the MPSS DSM where it must be shared during the whole
lifetime of the system.
I don't think that PAS releases the region. I checked the
qcom_q6v5_pas.c and there is only ioremap. The device stays loaded thus
the memory stays mapped.
Yes PAS does release the firmware region when the firmware is started,
qcom_scm_pas_metadata_release() does that.
We have already three of such "memory region devices" and we keep
growing it. It's not scalable.
If we want to properly describe this, we must then represent the MPSS subsystem
and associate this memory region.
Best regards,
Krzysztof
Thanks,
Neil
