Re: [PATCH 1/5] arm64: dts: qcom: x1e80100: Remove interconnect from SCM device

[Dmitry Baryshkov]

On Thu, Mar 12, 2026 at 09:26:35PM +0530, Maulik Shah wrote:
> Interconnect from SCM device are optional and were added to get
> additional performance benefit. These nodes however delays the
> SCM firmware device probe due to dependency on interconnect and
> results in NULL pointer dereference for the users of SCM device
> driver APIs, such as PDC driver.

This sounds like a bug in the PDC driver. It should reject being probed
before SCM is available.

> 
> Remove them from the scm device to unblock the user.
> 
> Signed-off-by: Maulik Shah <maulik.shah@xxxxxxxxxxxxxxxx>
> ---
>  arch/arm64/boot/dts/qcom/hamoa.dtsi | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/hamoa.dtsi b/arch/arm64/boot/dts/qcom/hamoa.dtsi
> index d7596ccf63b90a8a002ad6e77c0fb2c1b32ec9c8..ebecf43e0d462c431540257e299e3ace054901fd 100644
> --- a/arch/arm64/boot/dts/qcom/hamoa.dtsi
> +++ b/arch/arm64/boot/dts/qcom/hamoa.dtsi
> @@ -308,8 +308,7 @@ eud_in: endpoint {
>  	firmware {
>  		scm: scm {
>  			compatible = "qcom,scm-x1e80100", "qcom,scm";
> -			interconnects = <&aggre2_noc MASTER_CRYPTO QCOM_ICC_TAG_ALWAYS
> -					 &mc_virt SLAVE_EBI1 QCOM_ICC_TAG_ALWAYS>;
> +			/* TODO: add interconnects */

Somebody will try to fix this TODO, reverting this patch. Let's find a
better way to handle it (which would also fit other platforms).
Originaly this was proposed by Sibi ([1]) to speed up PAS
authentication. Other platforms require RPM or GCC clocks to let the
firmware access crypto core.

One of the (stupid) ideas would be to add a separate SCM (child?) device
which would be used for crypto-related SCM calls. I'd like to point out
that currently we bump those clocks or NoC bandwidth, but at the same
time we don't vote on the CX rail. I'm not sure of the firmware handles
that somehow or not.

[1] https://lore.kernel.org/all/1653289258-17699-1-git-send-email-quic_sibis@xxxxxxxxxxx/

>  			qcom,dload-mode = <&tcsr 0x19000>;
>  		};
>  
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry