lkml.org 
[lkml]   [2022]   [Nov]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] dt-bindings: reserved-memory: document Qualcomm MPSS DSM memory
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

>

\
 
 \ /
  Last update: 2022-11-18 14:33    [W:0.058 / U:0.880 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site