linux-kernel - [PATCH] firmware: arm_scmi: Set clock latency to U32

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Date:   Thu, 28 Apr 2022 13:29:13 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Cristian Marussi <cristian.marussi@....com>
Subject: [PATCH] firmware: arm_scmi: Set clock latency to U32_MAX if it is not supported

As per the spec, the clock_enable_delay is the worst case latency
incurred by the platform to enable the clock. The value of 0 indicates
that the platform doesn't support the same and must be considered as
maximum latency for practical purposes.

Currently the value of 0 is assigned as is and is propogated to the clock
framework which can assume that the clock can support atomic enable operation.

Fixes: 18f295b758b2 ("firmware: arm_scmi: Add support for clock_enable_latency")
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 drivers/firmware/arm_scmi/clock.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index 7a031afff389..2460979eabd2 100644
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/limits.h>
 #include <linux/sort.h>
 
 #include "protocols.h"
@@ -128,12 +129,13 @@ static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
 
 	ret = ph->xops->do_xfer(ph, t);
 	if (!ret) {
+		u32 latency;
 		attributes = le32_to_cpu(attr->attributes);
 		strlcpy(clk->name, attr->name, SCMI_MAX_STR_SIZE);
 		/* Is optional field clock_enable_latency provided ? */
 		if (t->rx.len == sizeof(*attr))
-			clk->enable_latency =
-				le32_to_cpu(attr->clock_enable_latency);
+			latency = le32_to_cpu(attr->clock_enable_latency);
+		clk->enable_latency = latency ? : U32_MAX;
 	}
 
 	ph->xops->xfer_put(ph, t);
-- 
2.36.0