Commit 850d64a4 authored by Prakash, Prashanth's avatar Prakash, Prashanth Committed by Rafael J. Wysocki
Browse files

ACPI / CPPC: acquire pcc_lock only while accessing PCC subspace 



We need to acquire pcc_lock only when we are accessing registers
that are in the PCC subspsace.

Signed-off-by: default avatarPrashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 5bbb86aa

drivers/acpi/cppc_acpi.c

+16 −14
Original line number Diff line number Diff line
@@ -763,7 +763,7 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps) 
	struct cpc_register_resource *highest_reg, *lowest_reg, *ref_perf,

								 *nom_perf;

	u64 high, low, ref, nom;

	int ret = 0;

	int ret = 0, regs_in_pcc = 0;



	if (!cpc_desc) {

		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
@@ -775,13 +775,13 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps) 
	ref_perf = &cpc_desc->cpc_regs[REFERENCE_PERF];

	nom_perf = &cpc_desc->cpc_regs[NOMINAL_PERF];



	spin_lock(&pcc_lock);



	/* Are any of the regs PCC ?*/

	if ((highest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||

		(lowest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||

		(ref_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||

		(nom_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) {

		spin_lock(&pcc_lock);

		regs_in_pcc = 1;

		/* Ring doorbell once to update PCC subspace */

		if (send_pcc_cmd(CMD_READ) < 0) {

			ret = -EIO;
@@ -808,6 +808,7 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps) 
		ret = -EFAULT;



out_err:

	if (regs_in_pcc)

		spin_unlock(&pcc_lock);

	return ret;

}
@@ -825,7 +826,7 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) 
	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);

	struct cpc_register_resource *delivered_reg, *reference_reg;

	u64 delivered, reference;

	int ret = 0;

	int ret = 0, regs_in_pcc = 0;



	if (!cpc_desc) {

		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
@@ -835,11 +836,11 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) 
	delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];

	reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];



	spin_lock(&pcc_lock);



	/* Are any of the regs PCC ?*/

	if ((delivered_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||

		(reference_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) {

		spin_lock(&pcc_lock);

		regs_in_pcc = 1;

		/* Ring doorbell once to update PCC subspace */

		if (send_pcc_cmd(CMD_READ) < 0) {

			ret = -EIO;
@@ -865,6 +866,7 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) 
	perf_fb_ctrs->prev_reference = reference;



out_err:

	if (regs_in_pcc)

		spin_unlock(&pcc_lock);

	return ret;

}
@@ -890,10 +892,9 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls) 


	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];



	spin_lock(&pcc_lock);



	/* If this is PCC reg, check if channel is free before writing */

	if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {

		spin_lock(&pcc_lock);

		ret = check_pcc_chan();

		if (ret)

			goto busy_channel;
@@ -912,6 +913,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls) 
			ret = -EIO;

	}

busy_channel:

	if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)

		spin_unlock(&pcc_lock);

	return ret;

}