Re: [PATCH V3 2/2] cpufreq: Add Loongson-3 CPUFreq driver support

[Xi Ruoyao]

On Fri, 2024-07-05 at 14:06 +0800, Huacai Chen wrote:
> Some of LoongArch processors (Loongson-3 series) support DVFS, their
> IOCSR.FEATURES has IOCSRF_FREQSCALE set. And they has a micro-core in
> the package called SMC (System Management Controller), which can be
> used to detect temperature, control fans, scale frequency and voltage,
> etc.
> 
> The Loongson-3 CPUFreq driver is very simple now, it communicate with
> SMC, get DVFS info, set target frequency from CPUFreq core, and so on.
> 
> There is a command list to interact with SMC, widely-used commands in
> the CPUFreq driver include:
> 
> CMD_GET_VERSION: Get SMC firmware version.
> 
> CMD_GET_FEATURE: Get enabled SMC features.
> 
> CMD_SET_FEATURE: Enable SMC features, such as basic DVFS, BOOST.
> 
> CMD_GET_FREQ_LEVEL_NUM: Get the number of all frequency levels.
> 
> CMD_GET_FREQ_BOOST_LEVEL: Get the first boost frequency level.
> 
> CMD_GET_FREQ_LEVEL_INFO: Get the detail info of a frequency level.
> 
> CMD_GET_FREQ_INFO: Get the current frequency.
> 
> CMD_SET_FREQ_INFO: Set the target frequency.
> 
> In future we will add automatic frequency scaling, which is similar to
> Intel's HWP (HardWare P-State).
> 
> Signed-off-by: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx

Hi Huacai,

I got some error with the driver enabled:

[    6.650403] BUG: using smp_processor_id() in preemptible [00000000] code: (udev-worker)/208
[    6.658719] caller is loongson3_cpufreq_probe+0x5c/0x250 [loongson3_cpufreq]

and the driver failed to probe.

It seems the caller of smp_processor_id is actually do_service_request,
which is inlined into loongson3_cpufreq_probe.

The .config file is attached.

-- 
Xi Ruoyao <xry111@xxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University

Attachment: config.gz
Description: application/gzip