linux-kernel - [PATCH 5.9 015/391] firmware: arm_scmi: Expand SMC/HVC message pool to more than one

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Date:   Tue,  3 Nov 2020 21:31:06 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peng Fan <peng.fan@....com>,
        Etienne Carriere <etienne.carriere@...aro.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 015/391] firmware: arm_scmi: Expand SMC/HVC message pool to more than one

From: Etienne Carriere <etienne.carriere@...aro.org>

[ Upstream commit 7adb2c8aaaa6a387af7140e57004beba2c04a4c6 ]

SMC/HVC can transmit only one message at the time as the shared memory
needs to be protected and the calls are synchronous.

However, in order to allow multiple threads to send SCMI messages
simultaneously, we need a larger poll of memory.

Let us just use value of 20 to keep it in sync mailbox transport
implementation. Any other value must work perfectly.

Link: https://lore.kernel.org/r/20201008143722.21888-4-etienne.carriere@linaro.org
Fixes: 1dc6558062da ("firmware: arm_scmi: Add smc/hvc transport")
Cc: Peng Fan <peng.fan@....com>
Signed-off-by: Etienne Carriere <etienne.carriere@...aro.org>
[sudeep.holla: reworded the commit message to indicate the practicality]
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/firmware/arm_scmi/smc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index a1537d123e385..22f83af6853a1 100644
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -149,6 +149,6 @@ static struct scmi_transport_ops scmi_smc_ops = {
 const struct scmi_desc scmi_smc_desc = {
 	.ops = &scmi_smc_ops,
 	.max_rx_timeout_ms = 30,
-	.max_msg = 1,
+	.max_msg = 20,
 	.max_msg_size = 128,
 };
-- 
2.27.0