Re: [PATCH] arm64: dts: qcom: sm8750: Add adsp fastrpc support

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

On 5/9/2025 4:27 AM, Konrad Dybcio wrote:
> On 5/9/25 12:20 AM, Alexey Klimov wrote:
>> On Fri May 2, 2025 at 10:38 AM BST, Konrad Dybcio wrote:
>>> On 5/2/25 3:15 AM, Alexey Klimov wrote:
>>>> While at this, also add required memory region for fastrpc.
>>>>
>>>> Tested on sm8750-mtp device with adsprpdcd.
>>>>
>>>> Cc: Ekansh Gupta <quic_ekangupt@quicinc.com>
>>>> Cc: Srinivas Kandagatla <srini@kernel.org>
>>>> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>>>> ---
>>>>  arch/arm64/boot/dts/qcom/sm8750.dtsi | 70 ++++++++++++++++++++++++++++
>>>>  1 file changed, 70 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/sm8750.dtsi b/arch/arm64/boot/dts/qcom/sm8750.dtsi
>>>> index 149d2ed17641..48ee66125a89 100644
>>>> --- a/arch/arm64/boot/dts/qcom/sm8750.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/sm8750.dtsi
>>>> @@ -7,6 +7,7 @@
>>>>  #include <dt-bindings/clock/qcom,sm8750-gcc.h>
>>>>  #include <dt-bindings/clock/qcom,sm8750-tcsr.h>
>>>>  #include <dt-bindings/dma/qcom-gpi.h>
>>>> +#include <dt-bindings/firmware/qcom,scm.h>
>>>>  #include <dt-bindings/interconnect/qcom,icc.h>
>>>>  #include <dt-bindings/interconnect/qcom,sm8750-rpmh.h>
>>>>  #include <dt-bindings/interrupt-controller/arm-gic.h>
>>>> @@ -523,6 +524,14 @@ llcc_lpi_mem: llcc-lpi@ff800000 {
>>>>  			reg = <0x0 0xff800000 0x0 0x800000>;
>>>>  			no-map;
>>>>  		};
>>>> +
>>>> +		adsp_rpc_remote_heap_mem: adsp-rpc-remote-heap {
>>>> +			compatible = "shared-dma-pool";
>>>> +			alloc-ranges = <0x0 0x00000000 0x0 0xffffffff>;
>>>> +			alignment = <0x0 0x400000>;
>>>> +			size = <0x0 0xc00000>;
>>>> +			reusable;
>>>> +		};
>>>>  	};
>>>>  
>>>>  	smp2p-adsp {
>>>> @@ -2237,6 +2246,67 @@ q6prmcc: clock-controller {
>>>>  						};
>>>>  					};
>>>>  				};
>>>> +
>>>> +				fastrpc {
>>>> +					compatible = "qcom,fastrpc";
>>>> +					qcom,glink-channels = "fastrpcglink-apps-dsp";
>>>> +					label = "adsp";
>>>> +					memory-region = <&adsp_rpc_remote_heap_mem>;
>>> IIUC the driver only considers this on the sensor DSP
>> Memory region is required for audio protection domain + adsprpdcd as far as I know.
> next-20250508
>
> rmem_node = of_parse_phandle(rdev->of_node, "memory-region", 0);
> if (domain_id == SDSP_DOMAIN_ID && rmem_node) {
> 	// ...
> }
>
> maybe some driver changes are still pending?

Would like to add some more details here:

Memory region is required for audio PD for dynamic loading and remote heap memory
requirements. Some initial memory(~2MB) is allocated initially when audio daemon
is getting attached[1] and this memory is added to audio PD memory pool.

Additionally, if there is some additional memory requirement from audio PD, the
PD can request for more memory using remote heap request[2]

The support for SDSP was added sometime back[3] to support SDSP usecases on some old
platform as there were no dedicated context banks for SDSP there. On recent platforms,
context banks are available wherever SDSP is supported. 

[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/misc/fastrpc.c#n1273
[2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/misc/fastrpc.c#n1884
[3] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/misc/fastrpc.c?id=c3c0363bc72d4d0907a6d446d7424b3f022ce82a

//Ekansh

>
> Konrad
>