recipes-kernel/linux/files/0001-i3c-i3c-hub-Fix-SMBus-Agent-tx-timeout-issue.patch

From 7bb82504ca6165b55716c22444ccc10c42e4392e Mon Sep 17 00:00:00 2001
From: Steven Niu <steven.niu.uj@renesas.com>
Date: Thu, 18 Sep 2025 17:53:12 +0800
Subject: [PATCH 1/2] i3c: i3c-hub: Fix SMBus Agent tx timeout issue

Background:
Sometimes the SMBus Agent may raise tx timeout issue.

Root Cause:
The TX_DONE status is cleared in IBI handler. IBI handler works in
workqueue context and may be disturbed by a new I2C API calling thread.
This may result in a condition that the new I2C tx API is called before
last TX_DONE is cleared. In this condition, the new tx action done will
not trigger an IBI.

Solution:
Remove the TX_DONE clearing action from IBI handler to the beginning of
SMBus Agent Tx action.

Signed-off-by: Steven Niu <steven.niu.uj@renesas.com>
---
 drivers/i3c/i3c-hub.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/i3c/i3c-hub.c b/drivers/i3c/i3c-hub.c
index 793438419f2b..2c655eb047dd 100644
--- a/drivers/i3c/i3c-hub.c
+++ b/drivers/i3c/i3c-hub.c
@@ -572,13 +572,6 @@ static void i3c_hub_agent_ibi(struct i3c_hub_smbus_agent *agent)
 		agent->tx_res = stat;
 		complete(&agent->completion);
 		spin_unlock_irqrestore(&agent->lock, flags);
-
-		ret = regmap_write(hub->regmap,
-				   HUB_REG_TP_SMBUS_AGNT_STS(agent->port_nr),
-				   HUB_REG_AGENT_CNTRL_STATUS_FINISH);
-		if (ret)
-			dev_warn(&hub->i3cdev->dev,
-				 "TP[%d] - failed to clear finish status\n", agent->port_nr);
 	}
 
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
@@ -727,6 +720,11 @@ static int i3c_hub_agent_i2c_xfer_one(struct i3c_hub_smbus_agent *agent,
 	}
 
 	reinit_completion(&agent->completion);
+	ret = regmap_write(hub->regmap,
+			   HUB_REG_TP_SMBUS_AGNT_STS(agent->port_nr),
+			   HUB_REG_AGENT_CNTRL_STATUS_FINISH);
+	if (ret)
+		dev_warn(dev, "TP[%d] - failed to clear finish status\n", agent->port_nr);
 
 	/* start transfer */
 	ret = regmap_write(hub->regmap, HUB_REG_TP_SMBUS_AGNT_TRANS_START, port_bit);
-- 
2.34.1