arm64: dts: qcom: kodiak: increase fastrpc compute-cb session slots

[PATCH] arm64: dts: qcom: kodiak: increase fastrpc compute-cb session slots

Posted by Jianping Li 13 hours ago

Some workloads on Kodiak can exhaust FastRPC sessions when multiple
compute clients open contexts concurrently, leading to -EBUSY failures.

Describe the compute context bank with qcom,nsessions = <5> so the
driver can provision enough session slots for the compute-cb instance.

Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/kodiak.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/qcom/kodiak.dtsi b/arch/arm64/boot/dts/qcom/kodiak.dtsi
index 6079e67ea829..5bd20909f9db 100644
--- a/arch/arm64/boot/dts/qcom/kodiak.dtsi
+++ b/arch/arm64/boot/dts/qcom/kodiak.dtsi
@@ -4465,6 +4465,7 @@ compute-cb@5 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <5>;
 						iommus = <&apps_smmu 0x1805 0x0>;
+						qcom,nsessions = <5>;
 						dma-coherent;
 					};
 				};
-- 
2.43.0

Re: [PATCH] arm64: dts: qcom: kodiak: increase fastrpc compute-cb session slots

Posted by Dmitry Baryshkov 9 hours ago

On Wed, Apr 01, 2026 at 03:33:45PM +0800, Jianping Li wrote:
> Some workloads on Kodiak can exhaust FastRPC sessions when multiple
> compute clients open contexts concurrently, leading to -EBUSY failures.
> 
> Describe the compute context bank with qcom,nsessions = <5> so the
> driver can provision enough session slots for the compute-cb instance.

This is a software property, so it probably should not have been added
to the DT in the first place. Can we replace it with the driver code,
allocating more sessions to the last CB?

> 
> Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/kodiak.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/kodiak.dtsi b/arch/arm64/boot/dts/qcom/kodiak.dtsi
> index 6079e67ea829..5bd20909f9db 100644
> --- a/arch/arm64/boot/dts/qcom/kodiak.dtsi
> +++ b/arch/arm64/boot/dts/qcom/kodiak.dtsi
> @@ -4465,6 +4465,7 @@ compute-cb@5 {
>  						compatible = "qcom,fastrpc-compute-cb";
>  						reg = <5>;
>  						iommus = <&apps_smmu 0x1805 0x0>;
> +						qcom,nsessions = <5>;
>  						dma-coherent;
>  					};
>  				};
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry

Re: [PATCH] arm64: dts: qcom: kodiak: increase fastrpc compute-cb session slots

Posted by Konrad Dybcio 9 hours ago

On 4/1/26 1:33 PM, Dmitry Baryshkov wrote:
> On Wed, Apr 01, 2026 at 03:33:45PM +0800, Jianping Li wrote:
>> Some workloads on Kodiak can exhaust FastRPC sessions when multiple
>> compute clients open contexts concurrently, leading to -EBUSY failures.
>>
>> Describe the compute context bank with qcom,nsessions = <5> so the
>> driver can provision enough session slots for the compute-cb instance.
> 
> This is a software property, so it probably should not have been added
> to the DT in the first place. Can we replace it with the driver code,
> allocating more sessions to the last CB?

Nov 2025 => https://lore.kernel.org/linux-arm-msm/53644b36-2eff-4b1c-9886-591afee8b589@oss.qualcomm.com/

Konrad