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

[Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>]

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@mainlining.org>
>> ---
> 
> +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@oss.qualcomm.com/
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/qcom/lemans.dtsi#n7500

//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 {
>>