[PATCH v4] i2c: davinci: fix division by zero on missing clock-frequency

[PATCH v4] 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 was defined in kHz (100), whereas the device tree property is
expected in Hz.

The probe function 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 redefining DAVINCI_I2C_DEFAULT_BUS_FREQ in Hz (100000)
to match the expected device tree property unit, allowing the existing
division logic to work correctly for both cases.

Fixes: b04ce6385979 ("i2c: davinci: kill platform data")
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>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---

Changes in v4:
- Restored accidentally removed blank lines (removed ninja changes).
- Collected Reviewed-by tag.

Changes in v3:
- Reverted probe function changes and correctly applied the fix to the macro.

Changes in v2:
- Changed approach: updated macro to Hz instead of dividing in probe.
- Added Fixes tag.

 drivers/i2c/busses/i2c-davinci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index a773ba082321..66c23535656b 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -117,7 +117,7 @@
 /* timeout for pm runtime autosuspend */
 #define DAVINCI_I2C_PM_TIMEOUT	1000	/* ms */
 
-#define DAVINCI_I2C_DEFAULT_BUS_FREQ	100
+#define DAVINCI_I2C_DEFAULT_BUS_FREQ	100000
 
 struct davinci_i2c_dev {
 	struct device           *dev;
-- 
2.43.0

Re: [PATCH v4] i2c: davinci: fix division by zero on missing clock-frequency

[Andi Shyti]

Hi Chaitanya,

On Tue, May 26, 2026 at 03:52:40PM +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 was defined in kHz (100), whereas the device tree property is
> expected in Hz.
> 
> The probe function 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 redefining DAVINCI_I2C_DEFAULT_BUS_FREQ in Hz (100000)
> to match the expected device tree property unit, allowing the existing
> division logic to work correctly for both cases.
> 
> Fixes: b04ce6385979 ("i2c: davinci: kill platform data")
> 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>
> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

merged to i2c/i2c-host-fixes.

Thanks,
Andi