Commit c7b79a752871 ("mfd: intel-lpss: Add Intel Alder Lake PCH-S PCI IDs") caused a regression on certain Gigabyte motherboards for Intel Alder Lake-S where system crashes to NULL pointer dereference in i2c_dw_xfer_msg() when system resumes from S3 sleep state ("deep").

I was able to debug the issue on Gigabyte Z690 AORUS ELITE and made following notes:

- Issue happens when resuming from S3 but not when resuming from "s2idle" - PCI device 00:15.0 == i2c_designware.0 is already in D0 state when system enters into pci_pm_resume_noirq() while all other i2c_designware PCI devices are in D3. Devices were runtime suspended and in D3 prior entering into suspend - Interrupt comes after pci_pm_resume_noirq() when device interrupts are re-enabled - According to register dump the interrupt really comes from the i2c_designware.0. Controller is enabled, I2C target address register points to a one detectable I2C device address 0x60 and the DW_IC_RAW_INTR_STAT register START_DET, STOP_DET, ACTIVITY and TX_EMPTY bits are set indicating completed I2C transaction.

My guess is that the firmware uses this controller to communicate with an on-board I2C device during resume but does not disable the controller before giving control to an operating system.

I was told the UEFI update fixes this but never the less it revealed the driver is not ready to handle TX_EMPTY (or RX_FULL) interrupt when device is supposed to be idle and state variables are not set (especially the dev->msgs pointer which may point to NULL or stale old data).

Introduce a new software status flag STATUS_ACTIVE indicating when the controller is active in driver point of view. Now treat all interrupts that occur when is not set as unexpected and mask all interrupts from the controller.

Fixes: c7b79a752871 ("mfd: intel-lpss: Add Intel Alder Lake PCH-S PCI IDs") Reported-by: Samuel Clark slc2015@gmail.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=215907 Cc: stable@vger.kernel.org # v5.12+ Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com --- Hans: Are you able to test this on your Baytrail collection with shared I2C controller and PUNIT so that patch doesn't break anything? I believe even if the Linux interrupt for such shared I2C controller is shared e.g. with the i2c-i801 the PUNIT access should not get affected by this interrupt masking. I think PUNIT access won't use interrupts but you never know... We have a MRD7 that has shared I2C controller with PUNIT but Linux interrupt is not shared. I.e. unexpected interrupt case and masking doesn't get hit. i2c-designware-slave.c is not fully in sync with this new status flag since STATUS_ACTIVE gets overwritten there and unexpected interrupt case is needlessly hit in case of shared interrupt and this controller is suspended but both of those can go to an another patchset. --- drivers/i2c/busses/i2c-designware-core.h | 7 +++++-- drivers/i2c/busses/i2c-designware-master.c | 13 +++++++++++++ 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h index 70b80e710990..4d3a3b464ecd 100644 --- a/drivers/i2c/busses/i2c-designware-core.h +++ b/drivers/i2c/busses/i2c-designware-core.h @@ -126,8 +126,9 @@ * status codes */ #define STATUS_IDLE 0x0 -#define STATUS_WRITE_IN_PROGRESS 0x1 -#define STATUS_READ_IN_PROGRESS 0x2 +#define STATUS_ACTIVE 0x1 +#define STATUS_WRITE_IN_PROGRESS 0x2 +#define STATUS_READ_IN_PROGRESS 0x4

/* * operation modes @@ -334,12 +335,14 @@ void i2c_dw_disable_int(struct dw_i2c_dev *dev);

static inline void __i2c_dw_enable(struct dw_i2c_dev *dev) { + dev->status |= STATUS_ACTIVE; regmap_write(dev->map, DW_IC_ENABLE, 1); }

static inline void __i2c_dw_disable_nowait(struct dw_i2c_dev *dev) { regmap_write(dev->map, DW_IC_ENABLE, 0); + dev->status &= ~STATUS_ACTIVE; }

void __i2c_dw_disable(struct dw_i2c_dev *dev); diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index 44a94b225ed8..dc3c5a15a95b 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -716,6 +716,19 @@ static int i2c_dw_irq_handler_master(struct dw_i2c_dev *dev) u32 stat;

stat = i2c_dw_read_clear_intrbits(dev); + + if (!(dev->status & STATUS_ACTIVE)) { + /* + * Unexpected interrupt in driver point of view. State + * variables are either unset or stale so acknowledge and + * disable interrupts for suppressing further interrupts if + * interrupt really came from this HW (E.g. firmware has left + * the HW active). + */ + regmap_write(dev->map, DW_IC_INTR_MASK, 0); + return 0; + } + if (stat & DW_IC_INTR_TX_ABRT) { dev->cmd_err |= DW_IC_ERR_TX_ABRT; dev->status = STATUS_IDLE;