Hi
On 11/11/21 8:57 AM, huangbibo wrote:
I2C interrupts may be triggered unexpectedly,
such as programs that directly access I2C registers,
bus conflicts caused by hardware design defects, etc.
These can cause null pointer reference errors and kernel panic.
kernel log:
[ 52.676442] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
...
[ 52.816536] Workqueue: efi_rts_wq efi_call_rts
[ 52.820968] pstate: 60000085 (nZCv daIf -PAN -UAO)
[ 52.825753] pc : i2c_dw_isr+0x36c/0x5e0 [i2c_designware_core]
[ 52.831487] lr : i2c_dw_isr+0x88/0x5e0 [i2c_designware_core]
[ 52.837134] sp : ffff8020fff17650
[ 52.924451] Call trace:
[ 52.926888] i2c_dw_isr+0x36c/0x5e0 [i2c_designware_core]
...
[ 52.957394] gic_handle_irq+0x7c/0x178
[ 52.961130] el1_irq+0xb0/0x140
[ 52.964259] 0x21291d30
[ 52.983729] 0x21160938
[ 52.986164] __efi_rt_asm_wrapper+0x28/0x44
[ 52.990335] efi_call_rts+0x78/0x448
[ 53.019021] Kernel panic - not syncing: Fatal exception in interrupt
Signed-off-by: huangbibo <huangbibo@xxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-master.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 2871cf2ee8b4..6af1ede38253 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -631,8 +631,14 @@ static int i2c_dw_irq_handler_master(struct dw_i2c_dev *dev)
if (stat & DW_IC_INTR_RX_FULL)
i2c_dw_read(dev);
- if (stat & DW_IC_INTR_TX_EMPTY)
- i2c_dw_xfer_msg(dev);
+ if (stat & DW_IC_INTR_TX_EMPTY) {
+ if (dev->msgs) {
+ i2c_dw_xfer_msg(dev);
+ } else { //null pointer
+ i2c_dw_disable_int(dev);
+ return 0;
+ }
+ }
This feels to me we are masking the problem. It's common to have
i2c-designware device suspended (and registers might read all bits zero)
and receive interrupts from another device if interrupt line is shared.
Also while dev->msgs is NULL.
I'd like to understand the issue more. Could you add
"i2c_designware_core.dyndbg=+p" into command line in order to see
dev_dbg() prints in dmesg and with following patch?
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -720,6 +720,7 @@ static int i2c_dw_irq_handler_master(struct
dw_i2c_dev *dev)
u32 stat;
stat = i2c_dw_read_clear_intrbits(dev);
+ dev_dbg(dev->dev, "stat %#x\n", stat);
if (stat & DW_IC_INTR_TX_ABRT) {
dev->cmd_err |= DW_IC_ERR_TX_ABRT;
dev->status = STATUS_IDLE;
Jarkko
