On 2025/4/10 1:10, Rafael J. Wysocki wrote:
> On Wed, Apr 9, 2025 at 8:57 AM Lifeng Zheng <zhenglifeng1@xxxxxxxxxx> wrote:
>>
>> Optimize cppc_get_perf() with three changes:
>>
>> 1. Change the error kind to "no such device" when pcc_ss_id < 0, as other
>> register value getting functions.
>>
>> 2. Add a check to verify if the register is supported to be read before
>> using it. The logic is:
>>
>> (1) If the register is of the integer type, check whether the register is
>> optional and its value is 0. If yes, the register is not supported.
>>
>> (2) If the register is of other types, a null one is not supported.
>>
>> 3. Return the result of cpc_read() instead of 0.
>>
>> Reviewed-by: Pierre Gondois <pierre.gondois@xxxxxxx>
>> Signed-off-by: Lifeng Zheng <zhenglifeng1@xxxxxxxxxx>
>> ---
>> drivers/acpi/cppc_acpi.c | 21 ++++++++++++++-------
>> 1 file changed, 14 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
>> index 39f019e265da..2f789d3b3cad 100644
>> --- a/drivers/acpi/cppc_acpi.c
>> +++ b/drivers/acpi/cppc_acpi.c
>> @@ -1201,20 +1201,29 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>>
>> reg = &cpc_desc->cpc_regs[reg_idx];
>>
>> + if (reg->type == ACPI_TYPE_INTEGER ?
>> + (IS_OPTIONAL_CPC_REG(reg_idx) && !reg->cpc_entry.int_value) :
>> + IS_NULL_REG(®->cpc_entry.reg)) {
>
> Please avoid using the ternary operator in any new kernel code.
>
> Why not write it this way
>
> if ((reg->type == ACPI_TYPE_INTEGER && IS_OPTIONAL_CPC_REG(reg_idx)
> && !reg->cpc_entry.int_value) || (reg->type != ACPI_TYPE_INTEGER &&
> IS_NULL_REG(®->cpc_entry.reg)) {
OK. Will replace it. Thanks!
>
>> + pr_debug("CPC register is not supported\n");
>> + return -EOPNOTSUPP;
>> + }
>> +
>> if (CPC_IN_PCC(reg)) {
>> int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
>> struct cppc_pcc_data *pcc_ss_data = NULL;
>> - int ret = 0;
>> + int ret;
>>
>> - if (pcc_ss_id < 0)
>> - return -EIO;
>> + if (pcc_ss_id < 0) {
>> + pr_debug("Invalid pcc_ss_id\n");
>> + return -ENODEV;
>> + }
>>
>> pcc_ss_data = pcc_data[pcc_ss_id];
>>
>> down_write(&pcc_ss_data->pcc_lock);
>>
>> if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
>> - cpc_read(cpunum, reg, perf);
>> + ret = cpc_read(cpunum, reg, perf);
>> else
>> ret = -EIO;
>>
>> @@ -1223,9 +1232,7 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>> return ret;
>> }
>>
>> - cpc_read(cpunum, reg, perf);
>> -
>> - return 0;
>> + return cpc_read(cpunum, reg, perf);
>> }
>>
>> /**
>> --
>
>
