Commit 45f3763a authored by Lifeng Zheng's avatar Lifeng Zheng Committed by Rafael J. Wysocki
Browse files

ACPI: CPPC: Optimize cppc_get_perf() 



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 ensure the pointer 'perf' is no null.

 3. 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.

 4. Return the result of cpc_read() instead of 0.

Reviewed-by: default avatarPierre Gondois <pierre.gondois@arm.com>
Signed-off-by: default avatarLifeng Zheng <zhenglifeng1@huawei.com>
Reviewed-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/20250411093855.982491-3-zhenglifeng1@huawei.com


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent e3d7935a

drivers/acpi/cppc_acpi.c

+17 −7
Original line number Diff line number Diff line
@@ -1184,6 +1184,9 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf) 
	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);

	struct cpc_register_resource *reg;



	if (perf == NULL)

		return -EINVAL;



	if (!cpc_desc) {

		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);

		return -ENODEV;
@@ -1191,20 +1194,29 @@ 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) || (reg->type != ACPI_TYPE_INTEGER &&

	     IS_NULL_REG(&reg->cpc_entry.reg))) {

		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;
@@ -1213,9 +1225,7 @@ 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);

}



/**