linux-kernel - [PATCH] cpufreq: scmi: Add quirk to disable checks in scmi_dev_used_by

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Message-Id: <20250814225155.3519000-1-florian.fainelli@broadcom.com>
Date: Thu, 14 Aug 2025 15:51:55 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: linux-kernel@...r.kernel.org
Cc: james.quinlan@...adcom.com,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Cristian Marussi <cristian.marussi@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Peng Fan <peng.fan@....com>,
	Mike Tipton <quic_mdtipton@...cinc.com>,
	arm-scmi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org
Subject: [PATCH] cpufreq: scmi: Add quirk to disable checks in scmi_dev_used_by_cpus()

Broadcom STB platforms were early adopters of the SCMI framework and as
a result, not all deployed systems have a Device Tree entry where SCMI
protocol 0x13 (PERFORMANCE) is declared as a clock provider, nor are the
CPU Device Tree node(s) referencing protocol 0x13 as their clock
provider.

Leverage the quirks framework recently introduce to match on the
Broadcom SCMI vendor and in that case, disable the Device Tree
properties checks being done by scmi_dev_used_by_cpus().

Suggested-by: Cristian Marussi <cristian.marussi@....com>
Fixes: 6c9bb8692272 ("cpufreq: scmi: Skip SCMI devices that aren't used by the CPUs")
Signed-off-by: Florian Fainelli <florian.fainelli@...adcom.com>
---
 drivers/cpufreq/scmi-cpufreq.c     | 13 +++++++++++++
 drivers/firmware/arm_scmi/quirks.c |  2 ++
 drivers/firmware/arm_scmi/quirks.h |  1 +
 3 files changed, 16 insertions(+)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index ef078426bfd5..80647511d3c3 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -22,6 +22,8 @@
 #include <linux/types.h>
 #include <linux/units.h>
 
+#include "../drivers/firmware/arm_scmi/quirks.h"
+
 struct scmi_data {
 	int domain_id;
 	int nr_opp;
@@ -34,6 +36,7 @@ struct scmi_data {
 static struct scmi_protocol_handle *ph;
 static const struct scmi_perf_proto_ops *perf_ops;
 static struct cpufreq_driver scmi_cpufreq_driver;
+static bool __maybe_unused scmi_cpufreq_dt_props_check_disable;
 
 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
 {
@@ -400,6 +403,9 @@ static bool scmi_dev_used_by_cpus(struct device *scmi_dev)
 	struct device *cpu_dev;
 	int cpu, idx;
 
+	if (scmi_cpufreq_dt_props_check_disable)
+		return true;
+
 	if (!scmi_np)
 		return false;
 
@@ -427,12 +433,19 @@ static bool scmi_dev_used_by_cpus(struct device *scmi_dev)
 	return false;
 }
 
+#define QUIRK_SCMI_CPUFREQ_CHECK_DT_PROPS			\
+	({							\
+		scmi_cpufreq_dt_props_check_disable = true;	\
+	})
+
 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 {
 	int ret;
 	struct device *dev = &sdev->dev;
 	const struct scmi_handle *handle;
 
+	SCMI_QUIRK(scmi_cpufreq_no_check_dt_props, QUIRK_SCMI_CPUFREQ_CHECK_DT_PROPS);
+
 	handle = sdev->handle;
 
 	if (!handle || !scmi_dev_used_by_cpus(dev))
diff --git a/drivers/firmware/arm_scmi/quirks.c b/drivers/firmware/arm_scmi/quirks.c
index 03960aca3610..aafc7b4b3294 100644
--- a/drivers/firmware/arm_scmi/quirks.c
+++ b/drivers/firmware/arm_scmi/quirks.c
@@ -171,6 +171,7 @@ struct scmi_quirk {
 /* Global Quirks Definitions */
 DEFINE_SCMI_QUIRK(clock_rates_triplet_out_of_spec, NULL, NULL, NULL);
 DEFINE_SCMI_QUIRK(perf_level_get_fc_force, "Qualcomm", NULL, "0x20000-");
+DEFINE_SCMI_QUIRK_EXPORTED(scmi_cpufreq_no_check_dt_props, "brcm-scmi", NULL, "0x2");
 
 /*
  * Quirks Pointers Array
@@ -181,6 +182,7 @@ DEFINE_SCMI_QUIRK(perf_level_get_fc_force, "Qualcomm", NULL, "0x20000-");
 static struct scmi_quirk *scmi_quirks_table[] = {
 	__DECLARE_SCMI_QUIRK_ENTRY(clock_rates_triplet_out_of_spec),
 	__DECLARE_SCMI_QUIRK_ENTRY(perf_level_get_fc_force),
+	__DECLARE_SCMI_QUIRK_ENTRY(scmi_cpufreq_no_check_dt_props),
 	NULL
 };
 
diff --git a/drivers/firmware/arm_scmi/quirks.h b/drivers/firmware/arm_scmi/quirks.h
index a71fde85a527..64ac1f05d0d3 100644
--- a/drivers/firmware/arm_scmi/quirks.h
+++ b/drivers/firmware/arm_scmi/quirks.h
@@ -48,5 +48,6 @@ static inline void scmi_quirks_enable(struct device *dev, const char *vend,
 /* Quirk delarations */
 DECLARE_SCMI_QUIRK(clock_rates_triplet_out_of_spec);
 DECLARE_SCMI_QUIRK(perf_level_get_fc_force);
+DECLARE_SCMI_QUIRK(scmi_cpufreq_no_check_dt_props);
 
 #endif /* _SCMI_QUIRKS_H */
-- 
2.34.1