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Message-ID: <CAJZ5v0jnF82WX_=4KtqwnLd=vcHYt_pbtyvQV74p0ojKr33D=A@mail.gmail.com>
Date: Tue, 10 Dec 2024 19:14:59 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lifeng Zheng <zhenglifeng1@...wei.com>
Cc: rafael@...nel.org, lenb@...nel.org, robert.moore@...el.com,
viresh.kumar@...aro.org, acpica-devel@...ts.linux.dev,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, linuxarm@...wei.com, jonathan.cameron@...wei.com,
zhanjie9@...ilicon.com, lihuisong@...wei.com, hepeng68@...wei.com,
fanghao11@...wei.com
Subject: Re: [PATCH v2 1/3] ACPI: CPPC: Refactor register get and set ABIs
On Fri, Nov 22, 2024 at 7:21 AM Lifeng Zheng <zhenglifeng1@...wei.com> wrote:
>
> Refactor register get and set ABIs using cppc_get_reg() and cppc_set_reg().
I don't quite like the cppc_get_reg() name. I think that
cppc_get_reg_val() would be better.
> Rename cppc_get_perf() to cppc_get_reg() as a generic function to read cppc
> registers, with two 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.
So it's not just a rename, but also a change in behavior. Can this
change in behavior become user-visible?
> Add cppc_set_reg() as a generic function for setting cppc registers.
Again, I would prefer cppc_set_reg_val().
> Unlike other set reg ABIs, this function 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.
And the new function is used to reduce some existing code duplication,
isn't it? Which would be good to mention here.
> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
> ---
> drivers/acpi/cppc_acpi.c | 191 +++++++++++++++------------------------
> 1 file changed, 72 insertions(+), 119 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index c1f3568d0c50..9aab22d8136a 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1179,10 +1179,13 @@ 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(int cpunum, enum cppc_regs reg_idx, u64 *val)
> {
> struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
> + struct cppc_pcc_data *pcc_ss_data = NULL;
Why are you moving this here? This change is not related to the rest
of the patch, is it?
> struct cpc_register_resource *reg;
> + int pcc_ss_id;
> + int ret = 0;
And here?
>
> if (!cpc_desc) {
> pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
> @@ -1191,20 +1194,23 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>
> reg = &cpc_desc->cpc_regs[reg_idx];
>
> + if (!CPC_SUPPORTED(reg)) {
> + pr_debug("CPC register (reg_idx=%d) is not supported\n", reg_idx);
> + 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;
> + pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
>
> if (pcc_ss_id < 0)
> - return -EIO;
> + 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);
> + cpc_read(cpunum, reg, val);
> else
> ret = -EIO;
>
> @@ -1213,21 +1219,65 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
> return ret;
> }
>
> - cpc_read(cpunum, reg, perf);
> + cpc_read(cpunum, reg, val);
>
> return 0;
> }
>
> +static int cppc_set_reg(int cpu, enum cppc_regs reg_idx, u64 val)
> +{
> + struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> + struct cppc_pcc_data *pcc_ss_data = NULL;
> + struct cpc_register_resource *reg;
> + int pcc_ss_id;
> + int ret;
> +
> + if (!cpc_desc) {
> + pr_debug("No CPC descriptor for CPU:%d\n", cpu);
> + return -ENODEV;
> + }
> +
> + reg = &cpc_desc->cpc_regs[reg_idx];
> +
> + if (!CPC_SUPPORTED(reg)) {
> + pr_debug("CPC register (reg_idx=%d) is not supported\n", reg_idx);
> + return -EOPNOTSUPP;
> + }
> +
> + if (CPC_IN_PCC(reg)) {
> + pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
Please declare the variables that are only needed in the PCC case here.
Also, I think it would be better to define a new function, say
cppc_set_reg_val_in_pcc() for this code and then have
if (CPC_IN_PCC(reg))
return cppc_set_reg_val_in_pcc(reg, val);
> +
> + 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;
> + }
> +
> + return cpc_write(cpu, reg, val);
> +}
> +
> /**
> * cppc_get_desired_perf - Get the desired performance register value.
> * @cpunum: CPU from which to get desired performance.
> * @desired_perf: Return address.
> *
> - * Return: 0 for success, -EIO otherwise.
> + * Return: 0 for success, -ERRNO otherwise.
> */
> int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
> {
> - return cppc_get_perf(cpunum, DESIRED_PERF, desired_perf);
> + return cppc_get_reg(cpunum, DESIRED_PERF, desired_perf);
> }
> EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
>
> @@ -1236,11 +1286,11 @@ EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
> * @cpunum: CPU from which to get nominal performance.
> * @nominal_perf: Return address.
> *
> - * Return: 0 for success, -EIO otherwise.
> + * Return: 0 for success, -ERRNO otherwise.
What do you mean by ERRNO?
> */
> int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
> {
> - return cppc_get_perf(cpunum, NOMINAL_PERF, nominal_perf);
> + return cppc_get_reg(cpunum, NOMINAL_PERF, nominal_perf);
> }
>
> /**
> @@ -1248,11 +1298,11 @@ int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
> * @cpunum: CPU from which to get highest performance.
> * @highest_perf: Return address.
> *
> - * Return: 0 for success, -EIO otherwise.
> + * Return: 0 for success, -ERRNO otherwise.
> */
> int cppc_get_highest_perf(int cpunum, u64 *highest_perf)
> {
> - return cppc_get_perf(cpunum, HIGHEST_PERF, highest_perf);
> + return cppc_get_reg(cpunum, HIGHEST_PERF, highest_perf);
> }
> EXPORT_SYMBOL_GPL(cppc_get_highest_perf);
>
> @@ -1261,11 +1311,11 @@ EXPORT_SYMBOL_GPL(cppc_get_highest_perf);
> * @cpunum: CPU from which to get epp preference value.
> * @epp_perf: Return address.
> *
> - * Return: 0 for success, -EIO otherwise.
> + * Return: 0 for success, -ERRNO otherwise.
Same here?
> */
> int cppc_get_epp_perf(int cpunum, u64 *epp_perf)
> {
> - return cppc_get_perf(cpunum, ENERGY_PERF, epp_perf);
> + return cppc_get_reg(cpunum, ENERGY_PERF, epp_perf);
> }
> EXPORT_SYMBOL_GPL(cppc_get_epp_perf);
It would be cleaner to do the changes below in a separate patch IMV.
> @@ -1545,44 +1595,14 @@ EXPORT_SYMBOL_GPL(cppc_set_epp_perf);
> */
> int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> {
> - struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
> - struct cpc_register_resource *auto_sel_reg;
> - u64 auto_sel;
> -
> - if (!cpc_desc) {
> - pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
> - return -ENODEV;
> - }
> -
> - auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
> -
> - if (!CPC_SUPPORTED(auto_sel_reg))
> - pr_warn_once("Autonomous mode is not unsupported!\n");
> -
> - if (CPC_IN_PCC(auto_sel_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 -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, auto_sel_reg, &auto_sel);
> - perf_caps->auto_sel = (bool)auto_sel;
> - } else {
> - ret = -EIO;
> - }
> -
> - up_write(&pcc_ss_data->pcc_lock);
> + u64 auto_sel;
> + int ret;
>
> + ret = cppc_get_reg(cpunum, AUTO_SEL_ENABLE, &auto_sel);
> + if (ret)
> return ret;
> - }
>
> + perf_caps->auto_sel = (bool)auto_sel;
> return 0;
> }
> EXPORT_SYMBOL_GPL(cppc_get_auto_sel_caps);
> @@ -1594,43 +1614,7 @@ EXPORT_SYMBOL_GPL(cppc_get_auto_sel_caps);
> */
> int cppc_set_auto_sel(int cpu, bool enable)
> {
> - int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> - struct cpc_register_resource *auto_sel_reg;
> - struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> - struct cppc_pcc_data *pcc_ss_data = NULL;
> - int ret = -EINVAL;
> -
> - if (!cpc_desc) {
> - pr_debug("No CPC descriptor for CPU:%d\n", cpu);
> - return -ENODEV;
> - }
> -
> - auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
> -
> - if (CPC_IN_PCC(auto_sel_reg)) {
> - if (pcc_ss_id < 0) {
> - pr_debug("Invalid pcc_ss_id\n");
> - return -ENODEV;
> - }
> -
> - if (CPC_SUPPORTED(auto_sel_reg)) {
> - ret = cpc_write(cpu, auto_sel_reg, enable);
> - 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);
> - } else {
> - ret = -ENOTSUPP;
> - pr_debug("_CPC in PCC is not supported\n");
> - }
> -
> - return ret;
> + return cppc_set_reg(cpu, AUTO_SEL_ENABLE, enable);
> }
> EXPORT_SYMBOL_GPL(cppc_set_auto_sel);
>
> @@ -1644,38 +1628,7 @@ EXPORT_SYMBOL_GPL(cppc_set_auto_sel);
> */
> int cppc_set_enable(int cpu, bool enable)
> {
> - int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> - struct cpc_register_resource *enable_reg;
> - struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> - struct cppc_pcc_data *pcc_ss_data = NULL;
> - int ret = -EINVAL;
> -
> - if (!cpc_desc) {
> - pr_debug("No CPC descriptor for CPU:%d\n", cpu);
> - return -EINVAL;
> - }
> -
> - enable_reg = &cpc_desc->cpc_regs[ENABLE];
> -
> - if (CPC_IN_PCC(enable_reg)) {
> -
> - if (pcc_ss_id < 0)
> - return -EIO;
> -
> - ret = cpc_write(cpu, enable_reg, enable);
> - 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 platfrom */
> - ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
> - up_write(&pcc_ss_data->pcc_lock);
> - return ret;
> - }
> -
> - return cpc_write(cpu, enable_reg, enable);
> + return cppc_set_reg(cpu, ENABLE, enable);
> }
> EXPORT_SYMBOL_GPL(cppc_set_enable);
>
> --
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