[Backport v4.3-branch] drivers: i2c: i2c_dw: fix target-mode ISR state races and missing START_DET unmask#111414
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[Backport v4.3-branch] drivers: i2c: i2c_dw: fix target-mode ISR state races and missing START_DET unmask#111414d3zd3z wants to merge 1 commit into
d3zd3z wants to merge 1 commit into
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…tate The target ISR gates write_requested() on `dw->state != CMD_SEND` so that back-to-back rx_full interrupts during a single write do not re-enter the callback. However, dw->state is only transitioned back to READY on stop_det. If the STOP interrupt is lost (glitch, bus reset, another master drives STOP while we are servicing the ISR), or if the master issues a repeated START with the same direction (WRITE-Sr-WRITE, which is legal in I2C), the state stays CMD_SEND forever and write_requested() is never called again for the rest of the target's life. i2c_dw_slave_read_clear_intr_bits() already handles start_det by resetting state to READY, but START_DET is not in the enabled interrupt mask in i2c_dw_slave_register(), so that path is dead code. Unmask START_DET so the boundary of every new (re)START on the bus is observed and state is correctly reset before the rx_full handler decides whether to call write_requested(). Signed-off-by: Sudarshan Iyengar <sudarshan.iyengar@alifsemi.com>
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Pull request overview
Backports a DesignWare I2C target (slave) fix onto v4.3-branch by enabling START condition detection interrupts so the slave state machine can reset on fresh START conditions, aligning behavior with the I2C target API contract described in the linked issue/PR.
Changes:
- Unmasks
START_DETin the slave-mode interrupt mask (i2c_dw_slave_register()).
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| write_intr_mask(DW_INTR_MASK_RX_FULL | DW_INTR_MASK_RD_REQ | | ||
| DW_INTR_MASK_TX_ABRT | DW_INTR_MASK_STOP_DET | | ||
| DW_INTR_MASK_START_DET, | ||
| reg_base); |
|
jhedberg
approved these changes
Jun 18, 2026
teburd
changed the title
teburd
approved these changes
Jun 23, 2026
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Backport of the fix from #107537 to
v4.3-branch.Fixes: #111412