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a=ed25519-sha256; t=1784547685; l=3397; i=aniket.randive@oss.qualcomm.com; s=20260325; h=from:subject:message-id; bh=P8NqVl1EFJ912fQvXrv3k+VINSrlyfLmQLx2G8wTsaU=; b=+3MTI4xr1BSlejyrCh1HNxgOlO94XP11FcKi9DNvkcOVKM4IXF3PNh5WqyMjMfLrkoM249QL3 kE8L/w389V4AfmSywdeNhXuWoP9oxs4wRLOf1Nsp4fYQwAgazKU4Bvz X-Developer-Key: i=aniket.randive@oss.qualcomm.com; a=ed25519; pk=4o37X1ZqGbCO/T2SR8kq/HnWvq0yb1RUlFuNukovbQk= X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIwMDEyOSBTYWx0ZWRfX+qBBPwFrqjPZ lXOr3SkSSqpzaFyAqQfGXaKnXApjKB4+cCSGT3kMzBhZmZWaj23ozySk5Xa/azlxZJ1hdgwD9cs 46ao3ZMuFjBqrR96CUiq1PtCIcaWV1k= X-Proofpoint-GUID: WvrjFA329cGhIHWFuuUvqwLWtpnwFkan X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIwMDEyOSBTYWx0ZWRfX5B4BOoyeba8A A7n7C+JNLkX0EMJxGZH5jJTTXqVNUeG7mCxLO2ynBn3nRjduuaZgwiEL6MLf1BmzUTIlNTfA5S1 efiWRFXMb/MnYvj050U7WbtMq7EBoWW1fJ5ZCCiL8K2uAW+zPi0VZcdoM86Gz6rbI7rSex3nJwJ XrVIMum95uDub50Jyq8kEgYJQj4oH84apvPxZR67HVvBY4CEfLMLeuqGrc6f0FuuLDYldTGT0dS wQqLqgkLNYGh4EIPmL0xZFCbMuqe/hnX7ZgQj5MqBdUrRFjhtUUP3juBBvgydV6GpLyU16HYwbH 5L0rdJJnjlgFY+S+I/XS8Fau95Hx45bnwQFVlemlgrK24M64byt3jWEVH76rBfK1pbGjgKbVN3B jEaPgUgWNKVx4l1u7J0bo7gprb42RlUP0S6F9szetNW4fGkSC3KSnqENKAkHG1W7KvKEXFOFnu7 Cp9hGouS9jPNmW/V+OQ== X-Proofpoint-ORIG-GUID: WvrjFA329cGhIHWFuuUvqwLWtpnwFkan X-Authority-Analysis: v=2.4 cv=foLsol4f c=1 sm=1 tr=0 ts=6a5e096d cx=c_pps a=rEQLjTOiSrHUhVqRoksmgQ==:117 a=fChuTYTh2wq5r3m49p7fHw==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=EUspDBNiAAAA:8 a=-hBw8TQWdD6LnWPIZ_AA:9 a=QEXdDO2ut3YA:10 a=2VI0MkxyNR6bbpdq8BZq:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-20_02,2026-07-20_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 suspectscore=0 priorityscore=1501 spamscore=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 malwarescore=0 adultscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607200129 The transfer timeout for an I2C controller should reflect the actual message length and bus frequency rather than a static 1-second value. A static timeout causes unnecessary delays on error paths for short messages, and may be insufficient for very long transfers. Add i2c_update_timeout() to i2c-core which computes a transfer-specific timeout and stores it directly in the standard adap->timeout field. The formula accounts for 9 bits per byte (8 data + 1 ACK) at the configured bus frequency. The caller supplies a safety multiplier and a minimum floor so that each driver retains full control over its timing policy without those values becoming public API. Storing the result in adap->timeout makes it visible to all consumers of that field, including the arbitration-loss retry loop in __i2c_transfer(). Signed-off-by: Aniket Randive --- drivers/i2c/i2c-core-base.c | 24 ++++++++++++++++++++++++ include/linux/i2c.h | 3 +++ 2 files changed, 27 insertions(+) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 3ec04787a737..3280652e20d8 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include #include @@ -2000,6 +2001,29 @@ void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_de } EXPORT_SYMBOL_GPL(i2c_parse_fw_timings); +/** + * i2c_update_timeout - compute and set a dynamic transfer timeout on an adapter + * @adap: the i2c_adapter whose timeout field will be updated + * @bus_freq_hz: I2C bus clock frequency in Hz + * @len: transfer length in bytes + * @safety_coeff: multiplier applied over the theoretical wire time + * @min_usec: minimum timeout floor in microseconds + * + * Computes a transfer-specific timeout from the message length and bus + * frequency, applies a safety multiplier and a minimum floor, then stores + * the result in adap->timeout (in jiffies). The caller supplies the policy + * constants so they remain internal to the driver. + */ +void i2c_update_timeout(struct i2c_adapter *adap, u32 bus_freq_hz, + size_t len, unsigned int safety_coeff, + unsigned int min_usec) +{ + u64 bit_usec = mul_u64_u32_div(len * 9, USEC_PER_SEC, bus_freq_hz); + + adap->timeout = usecs_to_jiffies(bit_usec * safety_coeff + min_usec); +} +EXPORT_SYMBOL_GPL(i2c_update_timeout); + /* ------------------------------------------------------------------------- */ int i2c_for_each_dev(void *data, int (*fn)(struct device *dev, void *data)) diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 14ab4d3055af..b52974eb7e58 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -912,6 +912,9 @@ void i2c_put_adapter(struct i2c_adapter *adap); unsigned int i2c_adapter_depth(struct i2c_adapter *adapter); void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults); +void i2c_update_timeout(struct i2c_adapter *adap, u32 bus_freq_hz, + size_t len, unsigned int safety_coeff, + unsigned int min_usec); /* Return the functionality mask */ static inline u32 i2c_get_functionality(struct i2c_adapter *adap) -- 2.34.1