All of lore.kernel.org
 help / color / mirror / Atom feed
From: Prashanth Prakash <pprakash@codeaurora.org>
To: linux-acpi@vger.kernel.org
Cc: rjw@rjwysocki.net, alexey.klimov@arm.com, hotran@apm.com,
	cov@codeaurora.org, Prashanth Prakash <pprakash@codeaurora.org>
Subject: [PATCH V3 2/7] ACPI/CPPC: acquire pcc_lock only while accessing PCC subspace
Date: Tue, 16 Aug 2016 14:39:39 -0600	[thread overview]
Message-ID: <1471379984-15712-3-git-send-email-pprakash@codeaurora.org> (raw)
In-Reply-To: <1471379984-15712-1-git-send-email-pprakash@codeaurora.org>

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

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
---
 drivers/acpi/cppc_acpi.c | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index fea58e2..93826c7 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -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)) {
+		(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;
@@ -808,7 +808,8 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
 		ret = -EFAULT;
 
 out_err:
-	spin_unlock(&pcc_lock);
+	if (regs_in_pcc)
+		spin_unlock(&pcc_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(cppc_get_perf_caps);
@@ -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;
@@ -865,7 +866,8 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
 	perf_fb_ctrs->prev_reference = reference;
 
 out_err:
-	spin_unlock(&pcc_lock);
+	if (regs_in_pcc)
+		spin_unlock(&pcc_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);
@@ -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;
@@ -912,7 +913,8 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 			ret = -EIO;
 	}
 busy_channel:
-	spin_unlock(&pcc_lock);
+	if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)
+		spin_unlock(&pcc_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(cppc_set_perf);
-- 
Qualcomm Datacenter Technologies on behalf of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.


  parent reply	other threads:[~2016-08-16 20:39 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-16 20:39 [PATCH V3 0/7] CPPC enhancements Prashanth Prakash
2016-08-16 20:39 ` [PATCH V3 1/7] ACPI/CPPC: restructure read/writes for efficient sys mapped reg ops Prashanth Prakash
2016-08-16 20:39 ` Prashanth Prakash [this message]
2016-08-16 20:39 ` [PATCH V3 3/7] ACPI/CPPC: support for batching CPPC requests Prashanth Prakash
2016-08-16 20:39 ` [PATCH V3 4/7] ACPI/CPPC: set a non-zero value for transition_latency Prashanth Prakash
2016-08-16 20:39 ` [PATCH V3 5/7] ACPI/CPPC: add sysfs support to compute delivered performance Prashanth Prakash
2016-08-16 20:39 ` [PATCH V3 6/7] ACPI/CPPC: move all PCC related information into pcc_data Prashanth Prakash
2016-08-16 20:39 ` [PATCH V3 7/7] ACPI/CPPC: check for error bit in PCC status field Prashanth Prakash
2016-08-26 23:43 ` [PATCH V3 0/7] CPPC enhancements Prakash, Prashanth
2016-09-12 11:15   ` Alexey Klimov
2016-09-12 22:07 ` Rafael J. Wysocki
2016-09-14 15:33   ` Prakash, Prashanth

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1471379984-15712-3-git-send-email-pprakash@codeaurora.org \
    --to=pprakash@codeaurora.org \
    --cc=alexey.klimov@arm.com \
    --cc=cov@codeaurora.org \
    --cc=hotran@apm.com \
    --cc=linux-acpi@vger.kernel.org \
    --cc=rjw@rjwysocki.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.