On 22.08.2025 12:52, Penny Zheng wrote:
> @@ -50,10 +141,335 @@ int __init amd_cppc_cmdline_parse(const char *s, const
> char *e)
> return 0;
> }
>
> +/*
> + * If CPPC lowest_freq and nominal_freq registers are exposed then we can
> + * use them to convert perf to freq and vice versa. The conversion is
> + * extrapolated as an linear function passing by the 2 points:
> + * - (Low perf, Low freq)
> + * - (Nominal perf, Nominal freq)
> + * Parameter freq is always in kHz.
> + */
> +static int amd_cppc_khz_to_perf(const struct amd_cppc_drv_data *data,
> + unsigned int freq, uint8_t *perf)
> +{
> + const struct xen_processor_cppc *cppc_data = data->cppc_data;
> + unsigned int mul, div;
> + int offset = 0, res;
> +
> + if ( cppc_data->cpc.lowest_mhz &&
> + data->caps.nominal_perf > data->caps.lowest_perf &&
> + cppc_data->cpc.nominal_mhz > cppc_data->cpc.lowest_mhz )
> + {
> + mul = data->caps.nominal_perf - data->caps.lowest_perf;
> + div = cppc_data->cpc.nominal_mhz - cppc_data->cpc.lowest_mhz;
> +
> + /*
> + * We don't need to convert to kHz for computing offset and can
> + * directly use nominal_mhz and lowest_mhz as the division
> + * will remove the frequency unit.
> + */
> + offset = data->caps.nominal_perf -
> + (mul * cppc_data->cpc.nominal_mhz) / div;
> + }
> + else
> + {
> + /* Read Processor Max Speed(MHz) as anchor point */
> + mul = data->caps.highest_perf;
> + div = this_cpu(pxfreq_mhz);
> + if ( !div )
> + return -EOPNOTSUPP;
> + }
> +
> + res = offset + (mul * freq) / (div * 1000);
> + if ( res > UINT8_MAX )
> + {
> + printk_once(XENLOG_WARNING
> + "Perf value exceeds maximum value 255: %d\n", res);
> + *perf = UINT8_MAX;
> + return 0;
> + }
> + if ( res <= 0 )
> + {
> + printk_once(XENLOG_WARNING
> + "Perf value smaller than minimum value 0: %d\n", res);
The message text doesn't fit the if() condition anymore. Perhaps simply
omit the "0" from the text? Then:
Acked-by: Jan Beulich <jbeul...@suse.com>
Jan
