[PATCH] i2c: davinci: fix division by zero on missing clock-frequency

[PATCH] i2c: davinci: fix division by zero on missing clock-frequency

[Chaitanya Sabnis]

When the 'clock-frequency' property is missing from the device tree,
the driver falls back to DAVINCI_I2C_DEFAULT_BUS_FREQ. However, this
macro is defined in kHz (100), whereas the device tree property is
expected in Hz.

The probe function blindly divided the fallback value by 1000, causing
integer truncation that resulted in dev->bus_freq = 0. This triggered
a deterministic division-by-zero kernel panic when calculating clock
dividers later in the probe sequence.

Fix this by isolating the division so it only applies to the Hz value
read from the device tree, cleanly assigning the kHz default otherwise.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260514044726.57297C2BCB7@smtp.kernel.org/
Signed-off-by: Chaitanya Sabnis <chaitanya.msabnis@gmail.com>
---
 drivers/i2c/busses/i2c-davinci.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index a773ba082321..bd0754abdcb7 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -760,9 +760,9 @@ static int davinci_i2c_probe(struct platform_device *pdev)
 
 	r = device_property_read_u32(&pdev->dev, "clock-frequency", &prop);
 	if (r)
-		prop = DAVINCI_I2C_DEFAULT_BUS_FREQ;
-
-	dev->bus_freq = prop / 1000;
+		dev->bus_freq = DAVINCI_I2C_DEFAULT_BUS_FREQ;
+	else
+		dev->bus_freq = prop / 1000;
 
 	dev->has_pfunc = device_property_present(&pdev->dev, "ti,has-pfunc");
 
-- 
2.43.0

Re: [PATCH] i2c: davinci: fix division by zero on missing clock-frequency

[Andrew Lunn]

On Thu, May 14, 2026 at 04:07:40PM +0530, Chaitanya Sabnis wrote:
> When the 'clock-frequency' property is missing from the device tree,
> the driver falls back to DAVINCI_I2C_DEFAULT_BUS_FREQ. However, this
> macro is defined in kHz (100), whereas the device tree property is
> expected in Hz.
> 
> The probe function blindly divided the fallback value by 1000, causing
> integer truncation that resulted in dev->bus_freq = 0. This triggered
> a deterministic division-by-zero kernel panic when calculating clock
> dividers later in the probe sequence.
> 
> Fix this by isolating the division so it only applies to the Hz value
> read from the device tree, cleanly assigning the kHz default otherwise.

Why not keep the patch simple and just change the value of
DAVINCI_I2C_DEFAULT_BUS_FREQ to Hz?

> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://lore.kernel.org/all/20260514044726.57297C2BCB7@smtp.kernel.org/
> Signed-off-by: Chaitanya Sabnis <chaitanya.msabnis@gmail.com>

Please also added a Fixes: tag.

       Andrew