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* [PATCH] firmware: arm_scmi: Populate fastchannel info only if set operations are allowed
@ 2023-11-13 14:32 Sudeep Holla
  2023-11-15 15:26 ` Cristian Marussi
  2023-11-16 18:25 ` Sudeep Holla
  0 siblings, 2 replies; 3+ messages in thread
From: Sudeep Holla @ 2023-11-13 14:32 UTC (permalink / raw)
  To: linux-arm-kernel; +Cc: Sudeep Holla, xinglong.yang, cristian.marussi

Certain SCMI performance domains may have restrictions on the set level
and/or limits operation. If the SCMI domain supports fastchannel and the
set operations are not allowed, then any attempts to fetch the fastchannel
information for set level and/or limits operation will result in the
SCMI platform returning SCMI_ERR_SUPPORT. However, since this information
about the domain is already known to the agent(OSPM here) obtained via
PERF_DOMAIN_ATTRIBUTES, the agent(OSPM) can avoid calls to the firmware
trying to fetch the fastchannel information for the same.

Add those checks and skip querying the fastchannel information from the
firmware based on the information collected during the domain enumeration
stage.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/firmware/arm_scmi/perf.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index f5a063b0b1ab..36cdcfaf4324 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -762,29 +762,36 @@ static void scmi_perf_domain_init_fc(const struct scmi_protocol_handle *ph,
 				     u32 domain, struct scmi_fc_info **p_fc)
 {
 	struct scmi_fc_info *fc;
+	struct perf_dom_info *dom;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return;
 
 	fc = devm_kcalloc(ph->dev, PERF_FC_MAX, sizeof(*fc), GFP_KERNEL);
 	if (!fc)
 		return;
 
-	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-				   PERF_LEVEL_SET, 4, domain,
-				   &fc[PERF_FC_LEVEL].set_addr,
-				   &fc[PERF_FC_LEVEL].set_db);
-
 	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
 				   PERF_LEVEL_GET, 4, domain,
 				   &fc[PERF_FC_LEVEL].get_addr, NULL);
 
-	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-				   PERF_LIMITS_SET, 8, domain,
-				   &fc[PERF_FC_LIMIT].set_addr,
-				   &fc[PERF_FC_LIMIT].set_db);
-
 	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
 				   PERF_LIMITS_GET, 8, domain,
 				   &fc[PERF_FC_LIMIT].get_addr, NULL);
 
+	if (dom->info.set_perf)
+		ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
+					   PERF_LEVEL_SET, 4, domain,
+					   &fc[PERF_FC_LEVEL].set_addr,
+					   &fc[PERF_FC_LEVEL].set_db);
+
+	if (dom->set_limits)
+		ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
+					   PERF_LIMITS_SET, 8, domain,
+					   &fc[PERF_FC_LIMIT].set_addr,
+					   &fc[PERF_FC_LIMIT].set_db);
+
 	*p_fc = fc;
 }
 
-- 
2.42.0


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2023-11-13 14:32 [PATCH] firmware: arm_scmi: Populate fastchannel info only if set operations are allowed Sudeep Holla
2023-11-15 15:26 ` Cristian Marussi
2023-11-16 18:25 ` Sudeep Holla

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