From f5cfe0a7158820118667f9574ac7e6df6eddc708 Mon Sep 17 00:00:00 2001 From: "William A. Kennington III" Date: Wed, 27 May 2026 20:09:52 +0000 Subject: [PATCH] i2c: designware: Handle active target cleanly When the I2C controller attempts a new transaction while the target controller is shutting down or restarting, it can lead to bus lockups and system bootloops if the hardware enters an inconsistent state. Address this by ensuring that the internal state machines are properly cleared when disabling the controller if target activity is detected. If the controller remains active after disabling, perform a bus recovery to reset it to a known good state. Signed-off-by: William A. Kennington III Reviewed-by: Andy Shevchenko Acked-by: Mika Westerberg Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20260527-dw-i2c-v5-4-3483057f8d67@wkennington.com --- drivers/i2c/busses/i2c-designware-common.c | 8 ++++++ drivers/i2c/busses/i2c-designware-master.c | 31 +++++++++++++--------- 2 files changed, 27 insertions(+), 12 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c index d792c65d46ae..e4dfa2ec58bb 100644 --- a/drivers/i2c/busses/i2c-designware-common.c +++ b/drivers/i2c/busses/i2c-designware-common.c @@ -633,6 +633,14 @@ void __i2c_dw_disable(struct dw_i2c_dev *dev) abort_needed = (raw_intr_stats & DW_IC_INTR_MST_ON_HOLD) || (ic_stats & DW_IC_STATUS_MASTER_HOLD_TX_FIFO_EMPTY); + + /* + * If we are in target mode and there is activity, we should also + * trigger an abort to clear the internal state machines. + */ + if (dev->mode == DW_IC_SLAVE && (ic_stats & DW_IC_STATUS_SLAVE_ACTIVITY)) + abort_needed = true; + if (abort_needed) { if (!(enable & DW_IC_ENABLE_ENABLE)) { regmap_write(dev->map, DW_IC_ENABLE, DW_IC_ENABLE_ENABLE); diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index de929b91d5ea..7a301c8b604e 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -785,18 +785,25 @@ __i2c_dw_xfer_one_part(struct dw_i2c_dev *dev, struct i2c_msg *msgs, size_t num) * IC_RAW_INTR_STAT.MASTER_ON_HOLD holding SCL low. Check if * controller is still ACTIVE before disabling I2C. */ - if (i2c_dw_is_controller_active(dev)) - dev_err(dev->dev, "controller active\n"); - - /* - * We must disable the adapter before returning and signaling the end - * of the current transfer. Otherwise the hardware might continue - * generating interrupts which in turn causes a race condition with - * the following transfer. Needs some more investigation if the - * additional interrupts are a hardware bug or this driver doesn't - * handle them correctly yet. - */ - __i2c_dw_disable_nowait(dev); + if (i2c_dw_is_controller_active(dev)) { + /* + * If the controller is still active after the timeout, attempt a + * bus recovery to clear any potentially locked state. + */ + dev_err(dev->dev, "controller active after xfer, recovering\n"); + i2c_recover_bus(&dev->adapter); + i2c_dw_init(dev); + } else { + /* + * We must disable the adapter before returning and signaling the end + * of the current transfer. Otherwise the hardware might continue + * generating interrupts which in turn causes a race condition with + * the following transfer. Needs some more investigation if the + * additional interrupts are a hardware bug or this driver doesn't + * handle them correctly yet. + */ + __i2c_dw_disable_nowait(dev); + } if (dev->msg_err) return dev->msg_err;