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Message-ID: <20250618102148.3085214-1-zhangjian.3032@bytedance.com>
Date: Wed, 18 Jun 2025 18:21:48 +0800
From: Jian Zhang <zhangjian.3032@...edance.com>
To: Ryan Chen <ryan_chen@...eedtech.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Joel Stanley <joel@....id.au>,
Andi Shyti <andi.shyti@...nel.org>,
Andrew Jeffery <andrew@...econstruct.com.au>,
linux-i2c@...r.kernel.org,
openbmc@...ts.ozlabs.org,
linux-arm-kernel@...ts.infradead.org,
linux-aspeed@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] i2c: aspeed: change debug level in irq handler
In interrupt context, using dev_err() can potentially cause latency
or affect system responsiveness due to printing to console.
In our scenario, under certain conditions, i2c1 repeatedly printed
"irq handled != irq. expected ..." around 20 times within 1 second.
Each dev_err() log introduced approximately 10ms of blocking time,
which delayed the handling of other interrupts — for example, i2c2.
At the time, i2c2 was performing a PMBus firmware upgrade. The
target device on i2c2 was time-sensitive, and the upgrade protocol
was non-retryable. As a result, the delay caused by frequent error
logging led to a timeout and ultimately a failed firmware upgrade.
Frequent error printing in interrupt context can be dangerous,
as it introduces latency and interferes with time-critical tasks.
This patch changes the log level from dev_err() to dev_dbg() to
reduce potential impact.
Signed-off-by: Jian Zhang <zhangjian.3032@...edance.com>
---
drivers/i2c/busses/i2c-aspeed.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index 1550d3d552ae..38e23c826f39 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -317,7 +317,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
switch (bus->slave_state) {
case ASPEED_I2C_SLAVE_READ_REQUESTED:
if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_ACK))
- dev_err(bus->dev, "Unexpected ACK on read request.\n");
+ dev_dbg(bus->dev, "Unexpected ACK on read request.\n");
bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
@@ -325,7 +325,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
break;
case ASPEED_I2C_SLAVE_READ_PROCESSED:
if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
- dev_err(bus->dev,
+ dev_dbg(bus->dev,
"Expected ACK after processed read.\n");
break;
}
@@ -354,7 +354,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
/* Slave was just started. Waiting for the next event. */;
break;
default:
- dev_err(bus->dev, "unknown slave_state: %d\n",
+ dev_dbg(bus->dev, "unknown slave_state: %d\n",
bus->slave_state);
bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
break;
@@ -459,7 +459,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
/* We are in an invalid state; reset bus to a known state. */
if (!bus->msgs) {
- dev_err(bus->dev, "bus in unknown state. irq_status: 0x%x\n",
+ dev_dbg(bus->dev, "bus in unknown state. irq_status: 0x%x\n",
irq_status);
bus->cmd_err = -EIO;
if (bus->master_state != ASPEED_I2C_MASTER_STOP &&
@@ -523,7 +523,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
goto error_and_stop;
} else if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
- dev_err(bus->dev, "slave failed to ACK TX\n");
+ dev_dbg(bus->dev, "slave failed to ACK TX\n");
goto error_and_stop;
}
irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
@@ -546,7 +546,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
fallthrough;
case ASPEED_I2C_MASTER_RX:
if (unlikely(!(irq_status & ASPEED_I2CD_INTR_RX_DONE))) {
- dev_err(bus->dev, "master failed to RX\n");
+ dev_dbg(bus->dev, "master failed to RX\n");
goto error_and_stop;
}
irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
@@ -577,7 +577,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
goto out_no_complete;
case ASPEED_I2C_MASTER_STOP:
if (unlikely(!(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))) {
- dev_err(bus->dev,
+ dev_dbg(bus->dev,
"master failed to STOP. irq_status:0x%x\n",
irq_status);
bus->cmd_err = -EIO;
@@ -589,7 +589,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
goto out_complete;
case ASPEED_I2C_MASTER_INACTIVE:
- dev_err(bus->dev,
+ dev_dbg(bus->dev,
"master received interrupt 0x%08x, but is inactive\n",
irq_status);
bus->cmd_err = -EIO;
@@ -665,7 +665,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
irq_remaining &= ~irq_handled;
if (irq_remaining)
- dev_err(bus->dev,
+ dev_dbg(bus->dev,
"irq handled != irq. expected 0x%08x, but was 0x%08x\n",
irq_received, irq_handled);
--
2.47.0
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