Hello Pierre,
On 2025/1/8 0:54, Pierre Gondois wrote:
> Hello Lifeng,
>
> On 12/20/24 09:30, zhenglifeng (A) wrote:
>> On 2024/12/17 21:48, Pierre Gondois wrote:
>>> Hello Lifeng,
>>>
>>> On 12/16/24 10:16, Lifeng Zheng wrote:
>>>> Rename cppc_get_perf() to cppc_get_reg_val() as a generic function to read
>>>> cppc registers, with four changes:
>>>>
>>>> 1. Change the error kind to "no such device" when pcc_ss_id < 0, which
>>>> means that this cpu cannot get a valid pcc_ss_id.
>>>>
>>>> 2. Add a check to verify if the register is a cpc supported one before
>>>> using it.
>>>>
>>>> 3. Extract the operations if register is in pcc out as
>>>> cppc_get_reg_val_in_pcc().
>>>>
>>>> 4. Return the result of cpc_read() instead of 0.
>>>>
>>>> Add cppc_set_reg_val_in_pcc() and cppc_set_reg_val() as generic functions
>>>> for setting cppc registers value. Unlike other set reg ABIs,
>>>> cppc_set_reg_val() checks CPC_SUPPORTED right after getting the register,
>>>> because the rest of the operations are meaningless if this register is not
>>>> a cpc supported one.
>>>>
>>>> These functions can be used to reduce some existing code duplication.
>>>>
>>>> Signed-off-by: Lifeng Zheng <zhenglifeng1@xxxxxxxxxx>
>>>> ---
>>>> drivers/acpi/cppc_acpi.c | 111 +++++++++++++++++++++++++++++----------
>>>> 1 file changed, 84 insertions(+), 27 deletions(-)
>>>>
>>>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
>>>> index c1f3568d0c50..bb5333a503a2 100644
>>>> --- a/drivers/acpi/cppc_acpi.c
>>>> +++ b/drivers/acpi/cppc_acpi.c
>>>> @@ -1179,43 +1179,100 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
>>>> return ret_val;
>>>> }
>>>> -static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>>>> +static int cppc_get_reg_val_in_pcc(int cpu, struct cpc_register_resource *reg, u64 *val)
>>>> {
>>>> - struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
>>>> + int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
>>>> + struct cppc_pcc_data *pcc_ss_data = NULL;
>>>> + int ret;
>>>> +
>>>> + 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)
>>>> + ret = cpc_read(cpu, reg, val);
>>>> + else
>>>> + ret = -EIO;
>>>> +
>>>> + up_write(&pcc_ss_data->pcc_lock);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int cppc_get_reg_val(int cpu, enum cppc_regs reg_idx, u64 *val)
>>>> +{
>>>> + struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
>>>> struct cpc_register_resource *reg;
>>>> if (!cpc_desc) {
>>>> - pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
>>>> + pr_debug("No CPC descriptor for CPU:%d\n", cpu);
>>>> return -ENODEV;
>>>> }
>>>> reg = &cpc_desc->cpc_regs[reg_idx];
>>>> - 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;
>>>> -
>>>> - if (pcc_ss_id < 0)
>>>> - return -EIO;
>>>> + if (!CPC_SUPPORTED(reg)) {
>>>> + pr_debug("CPC register (reg_idx=%d) is not supported\n", reg_idx);
>>>> + return -EOPNOTSUPP;
>>>> + }
>>>
>>> I think this is only valid for optional fields. Meaning that:
>>> - if the function is used one day for the mandatory 'Lowest Performance'
>>> field, an integer value of 0 would be valid.
>>> - if the function is used for a mandatory field containing a NULL Buffer,
>>> it seems we would return -EFAULT currently, through cpc_read(). -EOPNOTSUPP
>>> doesn't seem appropriate as the field would be mandatory.
>>>
>>> Maybe the function needs an additional 'bool optional' input parameter
>>> to do these check conditionally.
>>
>> Indeed, I should have judged the type before doing this check. But adding a
>> input parameter is not a really nice way to me. How about adding a bool
>> list of length MAX_CPC_REG_ENT in cppc_acpi.h to indicate wheter it is
>> optional?
>
> Actually all these functions:
> - cppc_get_desired_perf
> - cppc_get_highest_perf
> - cppc_get_epp_perf
> - cppc_set_epp
> - cppc_get_auto_act_window
> - cppc_set_auto_act_window
As you suggest in another patch, the logic should be placed in
cppc_get_auto_act_window() and some other functions. I'm afraid these
functions couldn't be implemented with the macros you suggest.
> - cppc_get_auto_sel
> - cppc_get_nominal_perf
>
> and in general all the functions getting / setting one value at a time could
> be implemented by macros similars to show_cppc_data(). From what I see the
> input parameters required are:
> - name of the field
> - if the field is mandatory to have or not
If with this parameter, we should put all the cppc_get_reg_val() and
cppc_set_reg_val() in the macro. This wouldn't look really nice. I
prefer to use a macro to judge mandatory / optional. I'll show you in
v4.
> - if the field is writeable
I think we can define a READ macro, a WRITE macro and a RW macro. For
the registers which are not writeable, only use the READ macro to
implement getting function.
> - if the field is implemented as an integer, register, or can be both
I don't think this parameter is necessary. The field type can be got
from cpc_desc->cpc_regs[reg_idx].type.
>
> This would avoid having numerous function definitions doing approximately the
> same thing.
So from what I see the input parameters required are name of the field
and reg_idx. Thanks for your advice!
>
>>
>>>
>>>> - pcc_ss_data = pcc_data[pcc_ss_id];
>>>> + if (CPC_IN_PCC(reg))
>>>> + return cppc_get_reg_val_in_pcc(cpu, reg, val);
>>>> - down_write(&pcc_ss_data->pcc_lock);
>>>> + return cpc_read(cpu, reg, val);
>>>> +}
>>>> - if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
>>>> - cpc_read(cpunum, reg, perf);
>>>> - else
>>>> - ret = -EIO;
>>>> +static int cppc_set_reg_val_in_pcc(int cpu, struct cpc_register_resource *reg, u64 val)
>>>> +{
>>>> + int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
>>>> + struct cppc_pcc_data *pcc_ss_data = NULL;
>>>> + int ret;
>>>> - up_write(&pcc_ss_data->pcc_lock);
>>>> + if (pcc_ss_id < 0) {
>>>> + pr_debug("Invalid pcc_ss_id\n");
>>>> + return -ENODEV;
>>>> + }
>>>> + ret = cpc_write(cpu, reg, val);
>>>> + if (ret)
>>>> return ret;
>>>> +
>>>> + pcc_ss_data = pcc_data[pcc_ss_id];
>>>> +
>>>> + down_write(&pcc_ss_data->pcc_lock);
>>>> + /* after writing CPC, transfer the ownership of PCC to platform */
>>>> + ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
>>>> + up_write(&pcc_ss_data->pcc_lock);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int cppc_set_reg_val(int cpu, enum cppc_regs reg_idx, u64 val)
>>>> +{
>>>> + struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
>>>> + struct cpc_register_resource *reg;
>>>> +
>>>> + if (!cpc_desc) {
>>>> + pr_debug("No CPC descriptor for CPU:%d\n", cpu);
>>>> + return -ENODEV;
>>>> }
>>>> - cpc_read(cpunum, reg, perf);
>>>> + reg = &cpc_desc->cpc_regs[reg_idx];
>>>> - return 0;
>>>> + if (!CPC_SUPPORTED(reg)) {
>>>> + pr_debug("CPC register (reg_idx=%d) is not supported\n", reg_idx);
>>>> + return -EOPNOTSUPP;
>>>> + }
>>>
>>> Similarly to cppc_get_reg_val(), if a field is:
>>> - mandatory + integer: currently doesn't exist. Not sure we should
>>> try to detect that, but might be safer.
>>> - mandatory + buffer: should not return -EOPNOTSUPP I think
>>> - optional + integer: e.g.: 'Autonomous Selection Enable Register',
>>> we should return -EOPNOTSUPP. It seems that currently, if the integer
>>> value is 1, I get a 'write error: Bad address'
>>> - optional + buffer:
>>> should effectively return -EOPNOTSUPP if the buffer is NULL.
>>
>> Actually, cpc_write() doesn't check field type and treats the field as a
>> buffer. That's why you get 'Bad address' error when the integer value is 1.
>> I think the existing code needs to be improved, otherwise there may be
>> unexpected problems.
>>
>> Do you mean we should return -EOPNOTSUPP no matter what to be written if
>> this field is a optional + integer one?
>
> Yes exact
>
>> And what about a mandatory +
>> integer one. Should we directly write the int_value?
>
> I don't think it is possible to have this. Indeed, if a value is writeable,
> it must be a register, so mandatory + integer should not exist. I suggested
> a check in case someone made a mistake, but it is not sure the check is actually
> necessary.
Yeah, I think it's better to have this check, too.
Regards,
Lifeng
>
> Regards,
> Pierre
>
