Re: [PATCH V6 5/5] arm64: dts: qcom: x1e80100: Enable cpufreq

[Sibi Sankar <quic_sibis@quicinc.com>]

On 7/3/24 01:43, Nikunj Kela wrote:
> 
> On 7/2/2024 12:59 PM, Sibi Sankar wrote:
>>
>>
>> On 7/2/24 21:25, Johan Hovold wrote:
>>> On Wed, Jun 12, 2024 at 06:10:56PM +0530, Sibi Sankar wrote:
>>>> Enable cpufreq on X1E80100 SoCs through the SCMI perf protocol node.
>>>>
>>>> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
>>>> ---
>>>>    arch/arm64/boot/dts/qcom/x1e80100.dtsi | 63
>>>> ++++++++++++++++----------
>>>>    1 file changed, 39 insertions(+), 24 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/x1e80100.dtsi
>>>> b/arch/arm64/boot/dts/qcom/x1e80100.dtsi
>>>> index 7b619db07694..d134dc4c7425 100644
>>>> --- a/arch/arm64/boot/dts/qcom/x1e80100.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/x1e80100.dtsi
>>>> @@ -69,8 +69,8 @@ CPU0: cpu@0 {
>>>>                reg = <0x0 0x0>;
>>>>                enable-method = "psci";
>>>>                next-level-cache = <&L2_0>;
>>>> -            power-domains = <&CPU_PD0>;
>>>> -            power-domain-names = "psci";
>>>> +            power-domains = <&CPU_PD0>, <&scmi_dvfs 0>;
>>>> +            power-domain-names = "psci", "perf";
>>>>                cpu-idle-states = <&CLUSTER_C4>;
>>>
>>>> +        scmi {
>>>> +            compatible = "arm,scmi";
>>>> +            mboxes = <&cpucp_mbox 0>, <&cpucp_mbox 2>;
>>>> +            mbox-names = "tx", "rx";
>>>> +            shmem = <&cpu_scp_lpri0>, <&cpu_scp_lpri1>;
>>>> +
>>>> +            #address-cells = <1>;
>>>> +            #size-cells = <0>;
>>>> +
>>>> +            scmi_dvfs: protocol@13 {
>>>> +                reg = <0x13>;
>>>> +                #power-domain-cells = <1>;
>>>> +            };
>>>> +        };
>>>>        };
>>>
>>
>> Hey Johan,
>>
>> Thanks for trying out the series.
>>
>>> This series gives a nice performance boost on the x1e80100 CRD, but I'm
>>> seeing a bunch of warnings and errors that need to be addressed:
>>>
>>> [    9.533053] arm-scmi firmware:scmi: Failed to get FC for protocol
>>> 13 [MSG_ID:6 / RES_ID:0] - ret:-95. Using regular messaging.
>>> [    9.549458] arm-scmi firmware:scmi: Failed to add opps_by_lvl at
>>> 3417600 for NCC - ret:-16
>>> [    9.563925] arm-scmi firmware:scmi: Failed to add opps_by_lvl at
>>> 3417600 for NCC - ret:-16
>>> [    9.572835] arm-scmi firmware:scmi: Failed to get FC for protocol
>>> 13 [MSG_ID:6 / RES_ID:1] - ret:-95. Using regular messaging.
>>> [    9.609471] arm-scmi firmware:scmi: Failed to add opps_by_lvl at
>>> 3417600 for NCC - ret:-16
>>> [    9.633341] arm-scmi firmware:scmi: Failed to add opps_by_lvl at
>>> 3417600 for NCC - ret:-16
>>> [    9.650000] arm-scmi firmware:scmi: Failed to get FC for protocol
>>> 13 [MSG_ID:6 / RES_ID:2] - ret:-95. Using regular messaging.
>>
>> X1E uses fast channels only for message-id: 7 (level set) and regular
>> channels for all the other messages. The spec doesn't mandate fast
>> channels for any of the supported message ids for the perf protocol.
>> So nothing to fix here.
>>
>>> [    9.727098] cpu cpu4: _opp_is_duplicate: duplicate OPPs detected.
>>> Existing: freq: 3417600000, volt: 0, enabled: 1. New: freq:
>>> 3417600000, volt: 0, enabled: 1
>>> [    9.737157] cpu cpu4: _opp_is_duplicate: duplicate OPPs detected.
>>> Existing: freq: 3417600000, volt: 0, enabled: 1. New: freq:
>>> 3417600000, volt: 0, enabled: 1
>>> [    9.875039] cpu cpu8: _opp_is_duplicate: duplicate OPPs detected.
>>> Existing: freq: 3417600000, volt: 0, enabled: 1. New: freq:
>>> 3417600000, volt: 0, enabled: 1
>>> [    9.888428] cpu cpu8: _opp_is_duplicate: duplicate OPPs detected.
>>> Existing: freq: 3417600000, volt: 0, enabled: 1. New: freq:
>>> 3417600000, volt: 0, enabled: 1
>>
>> The duplicate entries reported by the perf protocol come directly from
>> the speed bins. I was told the duplicate entry with volt 0 is meant to
>> indicate a lower power way of achieving the said frequency at a lower
>> core count. We have no way of using it in the kernel and it gets safely
>> discarded. So again nothing to fix in the kernel.
> 
> Hi Sibi,
> 
> Can you try increasing the max_msg_size to 256 bytes in mailbox
> transport? We saw the same issue but got resolved by increasing the
> max_msg_size for the transport(obviously, I reduced the max_msg to 10 to
> keep the total shmem size same). Even the opps_by_lvl warning went away
> with this for us.

Nikunj,
Thanks for taking time to review the series :)

Not sure if we are talking about the same things here, are you
suggesting that tweaking with the max_msg size will stop the SCMI
controller from reporting duplicate OPPs? Even if it does go away
magically wouldn't it mean you are dropping messages? Also opps_by_lvl
failing with -16 and duplicate opps detected in the opp core have the
same root cause i.e. duplicate entries reported by the controller.

> 
> Thanks,
> 
> -Nikunj
> 
>>
>>> [    9.913506] debugfs: Directory 'NCC' with parent 'pm_genpd'
>>> already present!
>>> [    9.922198] debugfs: Directory 'NCC' with parent 'pm_genpd'
>>> already present!
>>
>> Yeah I did notice ^^ during dev, the series isn't the one introducing it
>> so it shouldn't block the series acceptance. Meanwhile I'll spend some
>> cycles to get this warn fixed.

Johan,

https://lore.kernel.org/lkml/20240703110741.2668800-1-quic_sibis@quicinc.com/

Posted a fix for the warn ^^

>>
>> -Sibi
>>
>>>
>>> Johan
>>>