Re: [PATCH 3/4] arm64: dts: qcom: sdm630: describe adsp_mem region properly

[Ekansh Gupta]

On 17-04-2026 20:45, Ekansh Gupta wrote:
> On 15-04-2026 15:22, Konrad Dybcio wrote:
>> On 4/15/26 11:40 AM, Nickolay Goppen wrote:
>>> Downstream [1] this region is marked as shared and reusable so
>>> describe it that way.
>>>
>>> [1]: https://github.com/xiaomi-sdm660/android_kernel_xiaomi_sdm660/blob/11-EAS/arch/arm/boot/dts/qcom/sdm660.dtsi#L448
>>>
>>> Signed-off-by: Nickolay Goppen <setotau@xxxxxxxxxxxxxx>
>>> ---
>>
>> +Ekansh some insight, please?
>>
>> We're giving away that memory via qcom_scm_assign_mem() anyway
>> and I would assume that making it not-"no-map" could introduce issues
>> when the OS tries to access that region
>>
> With the current version and the upcoming planned enhancements, I don't
> see any major benefits of making this as not-"no-map".
> 
> With posted enhancements[1], the plan is to qcom_scm_assign_mem() the
> entire memory-region to lpass VMIDs. and un-assign it only during
> fastrpc_rpmsg_remove(). There have been implementation in downstream
> where this memory is dumped in case of SSR or audio PDR using minidump,
> so marking it `reusable` might make sense there, but that dump logic is
> not added upstream.
> 
> Upon checking the DT, I see a bigger problem here, this memory-region
> looks to me unused, it's not added under fastrpc adsp node(ref. [2]).
> Please correct me if I am wrong about this point.
> 
> [1]
> https://lore.kernel.org/all/20260409062617.1182-1-jianping.li@xxxxxxxxxxxxxxxx/
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/qcom/lemans.dtsi#n7500
Just had a new finding on this. There is one more reason why it is not
added as no-map in downstream. This audio PD carve-out region is not
defined for most of the platform's memory-map.

With a change to qcom_scm the memory during boot-up, issue was observed
on RB3Gen2[1], where EFI firmware was loaded in the memory region which
was causing boot-up issues.

So defining it as no-map might not be correct and it might need be
changed for all DT files.

I don't have a history of why it was added as a "no-map" region on
upstream but looks like same has been followed for almost all the
platforms. This needs to be modified based on the memory-maps and the
region needs to allocate memory in a dynamic manner.

[1] https://github.com/qualcomm-linux/kernel/pull/487

//Ekansh
> 
> //Ekansh
>> Konrad
>>
>>
>>>  arch/arm64/boot/dts/qcom/sdm630.dtsi | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sdm630.dtsi b/arch/arm64/boot/dts/qcom/sdm630.dtsi
>>> index 4b47efdb57b2..13094b5e9339 100644
>>> --- a/arch/arm64/boot/dts/qcom/sdm630.dtsi
>>> +++ b/arch/arm64/boot/dts/qcom/sdm630.dtsi
>>> @@ -495,8 +495,9 @@ venus_region: venus@9f800000 {
>>>  		};
>>>  
>>>  		adsp_mem: adsp-region@f6000000 {
>>> +			compatible = "shared-dma-pool";
>>>  			reg = <0x0 0xf6000000 0x0 0x800000>;
>>> -			no-map;
>>> +			reusable;
>>>  		};
>>>  
>>>  		qseecom_mem: qseecom-region@f6800000 {
>>>
>